Cisco SRS Telephony Overview

The Cisco SRS Telephony feature provides Cisco CallManager with fallback support for Cisco IP phones attached to a Cisco router on your local network. The SRS Telephony feature 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.

Feature Specifications for Cisco SRS Telephony, Version 2.02


Feature History
Release	SRST Version	Modification
12.1(5)YD	Version 1.0	•Cisco SRS Telephony introduced on the Cisco 2600 series and Cisco 3600 series multiservice routers, and Cisco IAD2420 series integrated access devices •Cisco IP phones able to establish a connection with an SRS Telephony router in the event of a WAN link to Cisco CallManager failure •Graying out of all Cisco IP phone function keys that are not supported during SRS Telephony operation •Extension-to-extension dialing •Direct Inward Dialing (DID) •Direct Outward Dialing (DOD) •Calling party ID (Caller ID/ANI) display •Last number redial •Preservation of local extension-to-extension calls when WAN link fails •Preservation of local extension to Public Switched Telephone Network (PSTN) calls when WAN link fails •Preservation of calls in progress when failed WAN link is reestablished •Blind transfer of calls within IP network •Multiple lines per Cisco IP phone •Multiple line appearance across telephones •Call hold (shared lines)
12.1(5)YD (cont.)	Version 1.0	•AnaLog Foreign Exchange Station (FXS) and Foreign Exchange Office (FXO) ports •BRI support for EuroISDN •PRI support for NET5 switch type
12.1(5)YD1	Version 1.0	Support was added for 144 Cisco IP phones on the Cisco 3660 multiservice routers.
12.2(2)XT	Version 2.0	•Cisco SRS Telephony was implemented on the Cisco 1750 and Cisco 1751 routers •Huntstop support •Class of restriction (COR) •Translation rule support •Music on hold and tone on hold •Distinctive ringing •Forward to a central voice mail or auto-attendant (AA) through PSTN during Cisco CallManager fallback •Phone number alias support during Cisco CallManager fallback: enhanced default destination support •List-based call restrictions for Cisco CallManager fallback
12.2(8)T	Version 2.0	Cisco SRS Telephony was integrated into Cisco IOS Release 12.2(8)T and implemented on the Cisco 3725 and Cisco 3745 routers, and Cisco MC3810-V3 concentrators.
12.2(8)T1	Version 2.0	Cisco SRS Telephony was implemented on the Cisco 2600-XM and Cisco 2691 routers.
12.2(11)T	Version 2.01	•Cisco SRS Telephony was implemented on the Cisco 1760 routers and support for Cisco 1750 was removed. •Support was added for additional connected Cisco IP phones •Support was added for additional directory numbers or virtual voice ports on Cisco IP phones
12.2(13)T	Version 2.02	•Unity Voice Mail Integration support was added, see the "Configuring Cisco SRS Telephony for Unity Voice-Mail Integration" section. •Directory number maximums were increased, see the "Memory Requirements" section. •Cisco SRS Telephony was implemented on the Cisco IP Conference Station 7935. •Cisco SRS Telephony was implemented on the Cisco Catalyst 4224 access gateway switches, Cisco Catalyst 4000 family access gateway modules, Cisco Catalyst 4224 access gateway switch, and Cisco 7200 routers (NPE-225, NPE-300, and NPE400). •Support was removed for the Cisco MC3810-V3 concentrator.
Supported Platforms
Cisco 1751 router, Cisco 1760 router, Cisco 2610 router, Cisco 2610-XM router, Cisco 2611 router, Cisco 2611-XM router, Cisco 2620 router, Cisco 2620-XM router, Cisco 2621, Cisco 2621-XM, Cisco 2650 router, Cisco 2650-XM router, Cisco 2651 router, Cisco 2651-XM router, Cisco 2691 router, Cisco 3620 router, Cisco 3640 router, Cisco 3640A router, Cisco 3660 router, Cisco 3725 router, Cisco 3745 router, Cisco Catalyst 4000 family access gateway modules, Cisco Catalyst 4224 access gateway switch, Cisco IAD2400 series, and Cisco 7200 routers ([Network Processing Engine] NPE-225, NPE-300, and NPE-400) Note Although the Cisco IAD2420 series supports the SRS Telephony feature, the Cisco IAD2420 is not recommended as an SRS Telephony solution for the enterprise branch office. The Cisco 1751 router does not support quality of service (QoS) features on the asymmetric digital subscriber line (ADSL) link, Cisco Hoot and Holler over IP applications, and G.SHDSL WAN card supported in the current Cisco 1700 image sets.
Supported IP Phones
Cisco IP Phone 7910, Cisco IP Phone 7940, Cisco IP Phone 7960

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.

Cisco Feature Navigator is a web-based tool that enables you to quickly 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://www.cisco.com/register

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

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, refer to the online release notes or, if supported, Cisco Feature Navigator.

Prerequisites

The following sections describe the prerequisites necessary for configuring Cisco SRS Telephony Version 2.02.

License Requirements

You must purchase a feature license to turn on this feature. You also need an account on Cisco.com to access Cisco IP phone firmware.

Memory Requirements

Table 1-1 lists the Cisco platforms, maximum number of Cisco IP phones, maximum number of directory numbers (DNs) or virtual voice ports, and memory requirements for Cisco IOS Release 12.2(13)T.

Note Although Cisco IOS software can provide a higher number of DNs for some of these platforms, the higher limitation may not apply to your platform due to memory restrictions. We recommend that you follow the guidelines in the Specifications tables to configure your network.

Table 1-1 Specifications for Version 2.02 Released in 12.2(13)T
Cisco Platform	Maximum Cisco IP Phones	Maximum DNs or Virtual Voice Ports	Minimum DRAM	Recommended DRAM¹	Minimum Flash	Recommended Flash	Cisco IOS Release
Cisco 1751 routers	24	120	64 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 1760 routers	24	120	64 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco IAD2400 series	24	120	64 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 2600-XM²	24	96	96 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 2650 router and Cisco 2651 router	48	192	96 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 2650-XM router and Cisco 2651-XM router	48	192	96 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 2691 router	72	288	128 MB	128 MB	32 MB	32 MB	12.2(13)T
Cisco 3620 (IP Plus image)	24	96	64 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 3620 (Enterprise Basic image)	24	96	64 MB	96 MB	16 MB	32 MB	12.2(13)T
Cisco 3640 and Cisco 3640A routers	72	288	96 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 3660 routers	240	960	96 MB	96 MB	32 MB	32 MB	12.2(13)T
Cisco 3725 routers	144	576	128 MB	128 MB	32 MB	32 MB	12.2(13)T
Cisco 3745 routers	240	960	128 MB	128 MB	32 MB	32 MB	12.2(13)T
Cisco Catalyst 4000 family access gateway modules³	24	48	64 MB	64 MB	32 MB	32 MB	12.2(13)T
Cisco Catalyst 4224 access gateway switches	48	192	128 MB	128 MB	48 MB	48 MB	12.2(13)T
Cisco 2600 series routers⁴	24	96	64 MB	—	16 MB	—	12.2(13)T
Cisco 7200 routers NPE-225	200	800	256 MB	256 MB	32 MB	32 MB	12.2(13)T
Cisco 7200 routers NPE-300 and NPE-400	240	960	256 MB	256 MB	32 MB	32 MB	12.2(13)T
Cisco 7200 routers NPE-400	480	960	512MB	512 MB	32 MB	32 MB	12.2(13)T

¹These DRAM recommendations were tested in Cisco IOS release 12.2(8)T for the maximum number of IP phones and virtual ports listed in this table. The DRAM recommendations for the number of IP phones and virtual ports listed have not been verified for subsequent Cisco IOS releases that have inherited Cisco SRS Telephony. Cisco SRS Telephony configurations running post Cisco IOS release 12.2(8)T software may require additional memory.

²Cisco 2610-XM, Cisco 2611-XM, Cisco 2620-XM, and Cisco 2621-XM.

³Minimum DRAM memory for IP Plus image is 64 MB; recommended DRAM memory for Enterprise Plus image is 128 MB.

⁴Cisco 2610, Cisco 2611, Cisco 2620, and Cisco 2621. Supports IP Plus Basic without Switching, IP Plus Basic without HD Analog/AIM ATM/Voice, and Enterprise Basic images only.

Cisco IP Phone Requirements

Cisco SRS Telephony, Version 2.02 supports the following Cisco IP phones:

•Cisco IP Phone 7910

•Cisco IP Conference Station 7935

•Cisco IP Phone 7940

•Cisco IP Phone 7960

Firmware Requirements

The appropriate Cisco IP phone firmware versions that support the Cisco IP Phone 7910, Cisco IP Phone 7940, and Cisco IP Phone 7960 models are P003E302, P004E302, or higher. The firmware version supporting the Cisco IP Conference Station 7935 is P00503010100.

The most current Cisco IP phone firmware versions are at http://www.cisco.com/cgi-bin/tablebuild.pl/ip-key.

Where to Go Next

•To configure basic functionality for SRS Telephony, see the "Configuring SRS Telephony on Routers to Support IP Phone Functions" section.

•To configure optional setting for Cisco SRS Telephony, see the "Configuring Cisco SRS Telephony Optional Settings" section.

•To configure Unity voice-mail integration, see the "Voice-Mail Integration Configuration Example" section.

Additional References

The following sections provide additional references related to Cisco SRS Telephony Version 2.02:

• Related Documents

• Standards

• MIBs

• RFCs

• Technical Assistance

Related Topic	Document Title
Cisco IP phones	• Getting Started with the Cisco IP Phone 7910 • Getting Started with the Cisco IP Phone 7960/7940 • Quick Reference Cisco IP Phone 7910 for Survivable Remote Site Telephony • Quick Reference Cisco IP Phone 7960/7940 for Survivable Remote Site Telephony
Command reference and configuration information for voice and telephony commands	• Cisco IOS Voice, Video, and Fax Command Reference, Release 12.2 T • Cisco IOS Voice, Video, and Fax Configuration Guide, Release 12.2 • Cisco IOS Debug Command Reference, Release 12.2
Cisco CallManager user documentation	• Cisco CallManager
Dynamic Host Control Protocol (DHCP)	• Cisco IOS DHCP Server

Standards


Standards¹	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—

¹Not all supported standards are listed.

MIBs


MIBs¹	MIBs Link
No new or modified MIBs are supported by this feature, and support for existing standards has not been modified by this feature.	To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL: http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

¹Not all supported MIBs are listed.

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

http://tools.cisco.com/ITDIT/MIBS/servlet/index

If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of supported MIBs and download MIBs from the Cisco MIBs page at the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

To access Cisco MIB Locator, 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://www.cisco.com/register

RFCs


RFCs¹	Title
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.	—

¹Not all supported RFCs are listed.

Technical Assistance


Description	Link
Technical Assistance Center (TAC) home page, containing 30,000 pages of searchable technical content, including links to products, technologies, solutions, technical tips, tools, and lots more. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/public/support/tac/home.shtml

Table Of Contents