Cisco SRST V3.4: Overview of Cisco IOS SRST

Table Of Contents

Overview of Cisco IOS SRST

Contents

Cisco SRST Description

H.323 Gateways and SRST

MGCP Gateways and SRST

Support for Cisco IP Phones, Platforms, Cisco CallManager, Signals, Languages, and Switches

Finding Cisco IOS Software Releases That Support Cisco SRST

Cisco IP Phone Support

Platform and Memory Support

Cisco CallManager Compatibility

Signal Support

Language Support

Switch Support

Prerequisites for Configuring Cisco SRST

Installing Cisco CallManager

Installing Cisco SRST

Integrating Cisco SRST with Cisco CallManager

Restrictions for Configuring Cisco SRST

Where to Go Next

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Overview of Cisco IOS SRST

This chapter describes Cisco Survivable Remote Site Telephony (SRST) and what it does. It also includes information about Cisco IP phone, platform, and Cisco CallManager version support; specifications; features; restrictions; and where to find additional reference documents.

Note For the most up-to-date information about Cisco IP phone support, the maximum number of Cisco IP phones, maximum DNs or virtual voice ports, and memory requirements for Cisco SRST, see the Cisco Survivable Remote Site Telephony (SRST) 3.4 Specifications for Cisco IOS Release 12.4(4)T at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/voice/srst/srst34/srs34spc.htm

Contents

• Cisco SRST Description

• Support for Cisco IP Phones, Platforms, Cisco CallManager, Signals, Languages, and Switches

• Prerequisites for Configuring Cisco SRST

• Restrictions for Configuring Cisco SRST

• Where to Go Next

• Additional References

Cisco SRST Description

Cisco SRST provides Cisco CallManager with fallback support for Cisco IP phones that are attached to a Cisco router on your local network. Cisco SRST enables routers to provide call-handling support for Cisco IP phones when they lose connection to remote primary, secondary, or tertiary Cisco CallManager installations or when the WAN connection is down.

Cisco CallManager supports Cisco IP phones at remote sites attached to Cisco multiservice routers across the WAN. Prior to Cisco SRST, when the WAN connection between a router and the Cisco CallManager failed or when connectivity with Cisco CallManager was lost for some reason, Cisco IP phones on the network became unusable for the duration of the failure. Cisco SRST overcomes this problem and ensures that the Cisco IP phones offer continuous (although minimal) service by providing call-handling support for Cisco IP phones directly from the Cisco SRST router. The system automatically detects a failure and uses Simple Network Auto Provisioning (SNAP) technology to autoconfigure the branch office router to provide call processing for Cisco IP phones that are registered with the router. When the WAN link or connection to the primary Cisco CallManager is restored, call handling reverts back to the primary Cisco CallManager.

When Cisco IP phones lose contact with primary, secondary, and tertiary Cisco CallManagers, they must establish a connection to a local Cisco SRST router to sustain the call-processing capability necessary to place and receive calls. The Cisco IP phone retains the IP address of the local Cisco SRST router as a default router in the Network Configuration area of the Settings menu. The Settings menu supports a maximum of five default router entries; however, Cisco CallManager accommodates a maximum of three entries. When a secondary Cisco CallManager is not available on the network, the local Cisco SRST router's IP address is retained as the standby connection for Cisco CallManager during normal operation.

Note Cisco CallManager fallback mode telephone service is available only to those Cisco IP phones that are supported by a Cisco SRST router. Other Cisco IP phones on the network remain out of service until they reestablish a connection with their primary, secondary, or tertiary Cisco CallManager.

Typically, it takes three times the keepalive period for a phone to discover that its connection to Cisco CallManager has failed. The default keepalive period is 30 seconds. If the phone has an active standby connection established with a Cisco SRST router, the fallback process takes 10 to 20 seconds after connection with Cisco CallManager is lost. An active standby connection to a Cisco SRST router exists only if the phone has the location of a single Cisco CallManager in its CallManager list. Otherwise, the phone activates a standby connection to its secondary Cisco CallManager.

Note The time it takes for an IP phone to fallback to the SRST router can vary depending on the phone type. Phones such as the Cisco 7902, Cisco 7905, and Cisco 7912 can take approximately 2.5 minutes to fallback to SRST mode.

If a Cisco IP phone has multiple Cisco CallManagers in its CallManager list, it progresses through its list of secondary and tertiary Cisco CallManagers before attempting to connect with its local Cisco SRST router. Therefore, the time that passes before the Cisco IP phone eventually establishes a connection with the Cisco SRST router increases with each attempt to contact to a Cisco CallManager. Assuming that each attempt to connect to a Cisco CallManager takes about one minute, the Cisco IP phone in question could remain offline for three minutes or more following a WAN link failure.

Note During a WAN connection failure, when Cisco SRST is enabled, Cisco IP phones display a message informing you that they are operating in Cisco CallManager fallback mode. The Cisco IP Phone 7960G and Cisco IP Phone 7940G display a "CM Fallback Service Operating" message, and the Cisco IP Phone 7910 displays a "CM Fallback Service" message when operating in Cisco CallManager fallback mode. When the Cisco CallManager is restored, the message goes away and full Cisco IP phone functionality is restored.

While in Cisco CallManager fallback mode, Cisco IP phones periodically attempt to reestablish a connection with Cisco CallManager at the central office. Generally the default time that Cisco IP phones wait before attempting to reestablish a connection to a remote Cisco CallManager is 120 seconds. The time can be changed in Cisco CallManager; see the "Device Pool Configuration Settings" chapter in the Cisco CallManager Administration Guide. A manual reboot can immediately reconnect Cisco IP phones to Cisco CallManager.

Once a connection is reestablished with Cisco CallManager, Cisco IP phones automatically cancel their registration with the Cisco SRST router. However, if a WAN link is unstable, Cisco IP phones can bounce between Cisco CallManager and Cisco SRST. A Cisco IP phone cannot reestablish a connection with the primary Cisco CallManager at the central office if it is currently engaged in an active call.

Figure 1 shows a branch office with several Cisco IP phones connected to a Cisco SRST router. The router provides connections to both a WAN link and the PSTN. The Cisco IP phones connect to their primary Cisco CallManager at the central office via this WAN link.

Figure 1 Branch Office Cisco IP Phones Connected to a Remote Central Cisco CallManager

Figure 2 shows the same branch office telephone network with the WAN connection down. In this situation, the Cisco IP phones use the Cisco SRST router as a fallback for their primary Cisco CallManager. The branch office Cisco IP phones are connected to the PSTN through the Cisco SRST router and are able to make and receive off-net calls.

Figure 2 Branch Office Cisco IP Phones Operating in SRST Mode

H.323 Gateways and SRST

On H.323 gateways, when the WAN link fails, active calls from Cisco IP phones to the PSTN are not maintained by default. Call preservation may work with the no h225 timeout keepalive command, but call preservation using the no h225 timeout keepalive command is not officially supported by Cisco Technical Support.

Under default configuration, the H.323 gateway maintains a keepalive signal with Cisco CallManager and terminates H.323-to-PSTN calls if the keepalive signal fails, for example if the WAN link fails. To disable this behavior and help preserve existing calls from local IP phones, you can use the no h225 timeout keepalive command. Disabling the keepalive mechanism only affects calls that will be torn down as a result of the loss of the H.225 keepalive signal. For information regarding disconnecting a call when an inactive condition is detected. see the Media Inactive Call Detection document.

MGCP Gateways and SRST

MGCP fallback is a different feature than SRST and, when configured as an individual feature, can be used by a PSTN gateway. To use SRST as your fallback mode on an MGCP gateway, SRST and MGCP fallback must both be configured on the same gateway. MGCP and SRST have had the capability to be configured on the same gateway since Cisco IOS Release 12.2(11)T.

To make outbound calls while in SRST mode on your MGCP gateway, two fallback commands must be configured on the MGCP gateway. These two commands allow SRST to assume control over the voice port and over call processing on the MGCP gateway. With Cisco IOS releases prior to 12.3(14)T, the two commands are the ccm-manager fallback-mgcp and call application alternate commands. With Cisco IOS releases after 12.3(14)T, the ccm-manager fallback-mgcp and service commands must be configured. A complete configuration for these commands is shown in the section "Enabling SRST on an MGCP Gateway" section on page 34.

Note The commands listed above are ineffective unless both commands are configured. For instance, your configuration will not work if you only configure the ccm-manager fallback-mgcp command.

For more information on the fallback methods for MGCP gateways, see the Configuring MGCP Gateway Support for Cisco CallManager document or the MGCP Gateway Fallback Transition to Default H.323 Session Application document.

Support for Cisco IP Phones, Platforms, Cisco CallManager, Signals, Languages, and Switches

The following sections provide information about Cisco Feature Navigator and the histories of Cisco IP phone, platform, and Cisco CallManager support from Cisco SRST Version 1.0 to the present version.

• Finding Cisco IOS Software Releases That Support Cisco SRST

• Cisco IP Phone Support

• Platform and Memory Support

• Cisco CallManager Compatibility

• Signal Support

• Language Support

• Switch Support

Finding Cisco IOS Software Releases That Support Cisco SRST

The tables in this chapter list only the Cisco IOS software releases that first introduce new features to Cisco SRST. Other Cisco IOS software releases may subsequently inherit versions of Cisco SRST. To get a list of Cisco IOS software releases that support a particular version of Cisco SRST, use Cisco Feature Navigator.

Cisco Feature Navigator is a web-based tool that enables you to determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.

To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions found at this URL:

http://tools.cisco.com/RPF/register/register.do

Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:

http://www.cisco.com/go/fn

Cisco IP Phone Support

For the most up-to-date information about Cisco IP phone support, see the Cisco IOS Survivable Remote Site Telephony (SRST) 3.4 Specifications for Cisco IOS Software Release 12.4(4)T at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/voice/srst/srst34/srs34spc.htm

The following IP phones are supported by Cisco SRST 3.4:

•Cisco Analog Telephone Adaptor (ATA) 186 and Cisco ATA 188 Version 2.16 and higher with Cisco CallManager 3.3 and higher

Cisco SRST supports Cisco ATA 186 and Cisco ATA 188 using Skinny Client Control Protocol (SCCP) for voice calls only

•Cisco IP Phone 7902G

•Cisco IP Phone 7905G

•Cisco IP Phone 7910

•Cisco IP Phone 7912G

•Cisco IP Phone Expansion Module 7914

•Cisco Wireless IP Phone 7920

•Cisco IP Conference Station 7935

•Cisco IP Conference Station 7936

•Cisco IP Phone 7940 and Cisco IP Phone 7940G

•Cisco IP Phone 7960 and Cisco IP Phone 7960G

•Cisco IP Phone 7970G

•Cisco IP Phone 7971G-GE

•Cisco VG224 Analog Phone Gateway, IOS Version 12.4(2)T with Cisco SRST 3.4 running Cisco IOS Software Releases 12.3(14)T, 12.4 mainline, and later. For configuration information see, the "Enabling Fallback to Cisco Unified SRST" section in SCCP Controlled Analog (FXS) Ports with Supplementary Features in Cisco IOS Gateways at http://www.cisco.com/en/US/products/ps6441/products_feature_guide09186a0080483a76.html.

•Cisco VG248 Analog Phone Gateway Version 1.2(1) and higher

Note During Cisco CallManager fallback, Cisco SRST considers the Cisco VG248 to be a group of Cisco IP phones. Cisco SRST counts each of the 48 ports on the Cisco VG248 as a separate Cisco IP phone. Support for Cisco VG248 Version 1.2(1) and higher is available as of Cisco SRST Version 2.1. For more information, see the Cisco VG248 Analog Phone Gateway Data Sheet and the Cisco VG248 Analog Phone Gateway Version 1.2(1) Release Notes.

Platform and Memory Support

For the most up-to-date information about the maximum number of Cisco IP phones, maximum DNs or virtual voice ports, and memory requirements for Cisco SRST, see the Cisco IOS Survivable Remote Site Telephony (SRST) 3.4 Specifications for Cisco IOS Software Release 12.4(4)T at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/voice/srst/srst34/srs34spc.htm

Determining Platform Support Through Cisco Feature Navigator

Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.

Availability of Cisco IOS Software Images

Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, see the online release notes or, if supported, Cisco Feature Navigator.

Note For the most up-to-date information about Cisco IOS software images, see the Cisco IOS Survivable Remote Site Telephony (SRST) 3.4 Specifications for Cisco IOS Software Release 12.4(4)T at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/voice/srst/srst34/srs34spc.htm

Cisco CallManager Compatibility

See the Cisco Call Manager Compatibility Matrix.

Signal Support

Cisco SRST supports FXS, FXO, T1, E1, and E1 R2 signals.

Language Support

Cisco SRST version 3.2 supports the following languages:

•Danish

•Dutch

•English

•French

•German

•Italian

•Japanese Katakana (available under Cisco CallManager V4.0 or later).

•Norwegian

•Portuguese

•Russian

•Spanish

•Sweden

Note The Cisco IP Phone 7970G and Cisco IP Phone 7971G-GE support English only.

Switch Support

Cisco SRST version 3.2 supports all PRI and BRI switches, including the following:

•basic-1tr6

•basic-5ess

•basic-dms100

•basic-net3

•basic-ni

•basic-ntt NTT switch type for Japan

•basic-ts013

•primary-4ess Lucent 4ESS switch type for the United States

•primary-5ess Lucent 5ESS switch type for the United States

•primary-dms100 Northern Telecom DMS-100 switch type for the United States

•primary-net5 NET5 switch type for the United Kingdom, Europe, Asia, and Australia

•primary-ni National ISDN switch type for the United States

•primary-ntt NTT switch type for Japan

•primary-qsig QSIG switch type

•primary-ts014 TS014 switch type for Australia (obsolete)

Prerequisites for Configuring Cisco SRST

Before configuring Cisco SRST you must do the following:

•You have an account on Cisco.com to download software.

To obtain an account on Cisco.com, go to www.cisco.com and click Register at the top of the screen.

•You have purchased a Cisco SRST license.

To purchase a license, go to http://www.cisco.com/cgi-bin/tablebuild.pl/ip-key.

•Choose an appropriate Cisco SRST version. Each SRST version supports a specific set of IP phones, memory requirements, features, and directory numbers (DNs). See the "Platform and Memory Support" section and the "Restrictions for Configuring Cisco SRST" section.

•Choose an appropriate phoneload. SRST only supports certain phoneloads that have been tested with the various Cisco CallManager versions. For the most up-to-date phoneloads, see the Cisco IOS Survivable Remote Site Telephony (SRST) 3.4 Specifications for Cisco IOS Software Release 12.4(4)T at the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/voice/srst/srst34/srs34spc.htm

•If you have Cisco CallManager already installed, verify that your version of Cisco CallManager is compatible with your Cisco SRST release. See the "Cisco CallManager Compatibility" section.

Installing Cisco CallManager

When installing Cisco CallManager consider the following:

•Follow the installation instructions under the appropriate Cisco CallManager version listed at http://www.cisco.com/univercd/cc/td/doc/product/voice/c_callmg/index.htm.

•Integrate Cisco SRST with Cisco CallManager. Integration is performed from Cisco CallManager. See "Integrating Cisco SRST with Cisco CallManager" section

Installing Cisco SRST

Cisco SRST versions have different installation instructions:

• Installing Cisco SRST V3.0 or Higher

• Installing Cisco SRST V2.0 and V2.1

• Installing Cisco SRST V1.0

To update Cisco SRST, follow the installation instructions described in this section.

Installing Cisco SRST V3.0 or Higher

Install the Cisco IOS software release image containing the Cisco SRST version that is compatible with your Cisco CallManager version. See the "Cisco CallManager Compatibility" section. Cisco IOS software can be downloaded from the Cisco Software Center at http://www.cisco.com/public/sw-center/.

Cisco SRST can be configured to support continuous multicast output of music on hold (MOH) from a flash MOH file in flash memory. For more information, see the "Configuring MOH from Flash Files" section on page 94. If you plan use music on hold, go to the Technical Support Software Download site at http://www.cisco.com/cgi-bin/tablebuild.pl/ip-iostsp and copy the music-on-hold.au file to the flash memory on your Cisco SRST router.

Installing Cisco SRST V2.0 and V2.1

Download and install Cisco SRST V2.0 or Cisco SRST V2.1 from the Cisco Software Center at http://www.cisco.com/public/sw-center/.

Installing Cisco SRST V1.0

Cisco SRST V1.0 runs with Cisco CallManager V3.0.5 only. It is recommended that you upgrade to the latest Cisco CallManager and Cisco SRST versions.

Integrating Cisco SRST with Cisco CallManager

There are two procedures for integrating Cisco SRST with Cisco CallManager. Procedure selection depends on the Cisco CallManager version that you have.

If You Have Cisco CallManager V3.3 or Later

If you have Cisco CallManager V3.3 or later, you must create an SRST reference and apply it to a device pool. An SRST reference is the IP address of the Cisco SRST router.

Step 1 Create an SRST reference.

a. From any page in Cisco CallManager, click System and SRST.

b. On the Find and List SRST References page, click Add a New SRST Reference.

c. On the SRST Reference Configuration page, enter a name in the SRST Reference Name field and the IP address of the Cisco SRST router in the IP Address field.

d. Click Insert.

Step 2 Apply the SRST reference or the default gateway to one or more device pools.

a. From any page in Cisco CallManager, click System and Device Pool.

b. On the Device Pool Configuration page, click on the desired device pool icon.

c. On the Device Pool Configuration page, choose an SRST reference or "Use Default Gateway" from the SRST Reference field's menu.

If You Have Cisco CallManager Prior to V3.3

If you have firmware versions that enable Cisco SRST by default, no additional configuration is required on CallManager to support Cisco SRST. If your firmware versions disable Cisco SRST by default, you must enable Cisco SRST for each phone configuration.

Step 1 Go to the Cisco CallManager Phone Configuration page.

a. From any page in Cisco CallManager, click Device and Phone.

b. In the Find and List Phones page, click Find.

c. After a list of phones appears, click on the desired device name.

d. The Phone Configuration appears.

Step 2 In the Phone Configuration page, go to the Product Specific Configuration section at the end of the page, choose Enabled from the Cisco SRST field's menu, and click Update.

Step 3 Go to the Phone Configuration page for the next phone and choose Enabled from the Cisco SRST field's menu by repeating Step 1 and Step 2.

Restrictions for Configuring Cisco SRST

Table 4 provides a history of restrictions from Cisco SRST Version 1.0 to the present version.

Table 4 History of Restrictions from Cisco SRST V1.0 to the Present Version

Cisco SRST
Version

Cisco IOS
Release

Restrictions

Version 3.4

12.4(4)T

•All of the restrictions in Cisco SRST Version 1.0.

•Call transfer is supported only on the following:

–VoIP H.323, VoFR, and VoATM between Cisco gateways running Cisco IOS Release 12.2(11)T and using the H.323 nonstandard information element

–FXO and FXS loop-start (analog)

–FXO and FXS ground-start (analog)

–Ear and mouth (E&M) (analog) and DID (analog)

–T1 channel-associated signaling (CAS) with FXO and FXS ground-start signaling

–T1 CAS with E&M signaling

–All PRI and BRI switch types

•The following Cisco IP phone function keys are dimmed because they are not supported during SRST operation:

–MeetMe

–GPickUp (group pickup)

–Park

–Confrn (conference)

•Although the Cisco IAD2420 series integrated access devices (IADs) support the Cisco SRST feature, this feature is not recommended as a solution for enterprise branch offices.

Version 3.3

12.3(14)T

Version 3.2

12.3(11)T

Version 3.1

12.3(7)T

Version 3.0

12.2(15)ZJ

Version 2.1

12.2(15)T

Version 2.02

12.2(13)T

Version 2.01

12.2(11)T

Version 2.0

12.2(8)T1

Version 2.0

12.2(8)T

Version 2.0

12.2(2)XT

Version 1.0

12.2(2)XB

•Does not support first generation Cisco IP phones, such as Cisco IP Phone 30 VIP and Cisco IP Phone 12 SP+.

•Does not support other Cisco CallManager applications or services: Cisco IP SoftPhone, Cisco uOne—Voice and Unified Messaging Application, or Cisco IP Contact Center.

•Does not support Centralized Automatic Message Accounting (CAMA) trunks on the Cisco 3660 routers.

Note If you are in one of the states in the United States of America where there is a regulatory requirement for CAMA trunks to interface to 911 emergency services, and you would like to connect more than 48 Cisco IP phones to the Cisco 3660 multiservice routers in your network, contact your local Cisco account team for help in understanding and meeting the CAMA regulatory requirements.

12.2(2)XG

12.1(5)YD

Where to Go Next

The next chapters of this guide describe how to configure Cisco SRST. As shown in Table 5, each chapter takes you through these tasks in the order in which they need to be performed. The first task for configuring Cisco SRST is to ensure that the basic software and hardware in your system is configured correctly for Cisco SRST. For instructions, see the "Prerequisites for Configuring Cisco SRST" section.

Table 5 Cisco SRST Configuration Sequence

Task

Where Task Is Described

1. Setting up a Cisco SRST system to communicate with your network

" Setting Up the Network" chapter

2. Setting up the basic Cisco SRST phone configuration

" Setting Up Cisco IP Phones" chapter

3. Configuring incoming and outgoing calls

" Setting Up Call Handling" chapter

4. Configuring optional system and phone parameters

" Configuring Additional Call Features" chapter

5. Configuring optional security for SRST

" Setting Up Secure SRST" chapter

6. Setting up voice mail

" Integrating Voice Mail with Cisco SRST" chapter

Additional References

The following sections provide additional references related to Cisco SRST:

• Related Documents

• Standards

• MIBs

• RFCs

• Technical Assistance

Related Documents

Related Topic

Documents

SRST Commands

• Cisco IOS Survivable Remote Site Telephony (SRST) Command Reference (All Versions)

Cisco IP phones

• Cisco IP Phone 7902 Quick Start Guide

• Cisco IP Phone 7902G Quick Start Guide

• Getting Started with the Cisco IP Phone 7910

• At a Glance Cisco IP Phone 7912G

• Cisco IP Phone 7914 Expansion Module Quick Start Guide

• Cisco IP Conference Station 7935 Documents

• Phone Guide Cisco IP Phone 7960 and 7940 Series

• Cisco IP Phone 7960 and 7940 Series User Guide

Command reference and configuration information for voice and telephony commands

• Cisco IOS Voice Command Reference

• Cisco IOS Debug Command Reference

Configuring SRS Telephony and MGCP Fallback

• Configuring MGCP Gateway Support for Cisco CallManager

• MGCP Gateway Fallback Transition to Default H.323 Session Application

• Configuring SRS Telephony and MGCP Fallback

Cisco CallManager user documentation

• Cisco CallManager

DHCP

• Cisco IOS DHCP Server

Media Inactive Call Detection

• Media Inactive Call Detection

Standard Preface

•Cisco IOS Voice Configuration Library Preface

Standard Glossary

•Cisco IOS Voice Configuration Library Glossary

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—

MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

—

Technical Assistance

Description

Link

The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/techsupport

Cisco SRST Version	Cisco IOS Release	Restrictions
Version 3.4	12.4(4)T	•All of the restrictions in Cisco SRST Version 1.0. •Call transfer is supported only on the following: –VoIP H.323, VoFR, and VoATM between Cisco gateways running Cisco IOS Release 12.2(11)T and using the H.323 nonstandard information element –FXO and FXS loop-start (analog) –FXO and FXS ground-start (analog) –Ear and mouth (E&M) (analog) and DID (analog) –T1 channel-associated signaling (CAS) with FXO and FXS ground-start signaling –T1 CAS with E&M signaling –All PRI and BRI switch types •The following Cisco IP phone function keys are dimmed because they are not supported during SRST operation: –MeetMe –GPickUp (group pickup) –Park –Confrn (conference) •Although the Cisco IAD2420 series integrated access devices (IADs) support the Cisco SRST feature, this feature is not recommended as a solution for enterprise branch offices.
Version 3.3	12.3(14)T
Version 3.2	12.3(11)T
Version 3.1	12.3(7)T
Version 3.0	12.2(15)ZJ
Version 2.1	12.2(15)T
Version 2.02	12.2(13)T
Version 2.01	12.2(11)T
Version 2.0	12.2(8)T1
Version 2.0	12.2(8)T
Version 2.0	12.2(2)XT
Version 1.0	12.2(2)XB	•Does not support first generation Cisco IP phones, such as Cisco IP Phone 30 VIP and Cisco IP Phone 12 SP+. •Does not support other Cisco CallManager applications or services: Cisco IP SoftPhone, Cisco uOne—Voice and Unified Messaging Application, or Cisco IP Contact Center. •Does not support Centralized Automatic Message Accounting (CAMA) trunks on the Cisco 3660 routers. Note If you are in one of the states in the United States of America where there is a regulatory requirement for CAMA trunks to interface to 911 emergency services, and you would like to connect more than 48 Cisco IP phones to the Cisco 3660 multiservice routers in your network, contact your local Cisco account team for help in understanding and meeting the CAMA regulatory requirements.
	12.2(2)XG
	12.1(5)YD
	12.1(5)YD

Task	Where Task Is Described
1. Setting up a Cisco SRST system to communicate with your network	" Setting Up the Network" chapter
2. Setting up the basic Cisco SRST phone configuration	" Setting Up Cisco IP Phones" chapter
3. Configuring incoming and outgoing calls	" Setting Up Call Handling" chapter
4. Configuring optional system and phone parameters	" Configuring Additional Call Features" chapter
5. Configuring optional security for SRST	" Setting Up Secure SRST" chapter
6. Setting up voice mail	" Integrating Voice Mail with Cisco SRST" chapter

Related Topic	Documents
SRST Commands	• Cisco IOS Survivable Remote Site Telephony (SRST) Command Reference (All Versions)
Cisco IP phones	• Cisco IP Phone 7902 Quick Start Guide • Cisco IP Phone 7902G Quick Start Guide • Getting Started with the Cisco IP Phone 7910 • At a Glance Cisco IP Phone 7912G • Cisco IP Phone 7914 Expansion Module Quick Start Guide • Cisco IP Conference Station 7935 Documents • Phone Guide Cisco IP Phone 7960 and 7940 Series • Cisco IP Phone 7960 and 7940 Series User Guide
Command reference and configuration information for voice and telephony commands	• Cisco IOS Voice Command Reference • Cisco IOS Debug Command Reference
Configuring SRS Telephony and MGCP Fallback	• Configuring MGCP Gateway Support for Cisco CallManager • MGCP Gateway Fallback Transition to Default H.323 Session Application • Configuring SRS Telephony and MGCP Fallback
Cisco CallManager user documentation	• Cisco CallManager
DHCP	• Cisco IOS DHCP Server
Media Inactive Call Detection	• Media Inactive Call Detection
Standard Preface	•Cisco IOS Voice Configuration Library Preface
Standard Glossary	•Cisco IOS Voice Configuration Library Glossary