Cisco SIP SRST V3.4: Configuring the SIP Registrar

Configuring the SIP Registrar

SIP registrar functionality in Cisco IOS software is an essential part of both Version 3.0 and Version 3.4 Cisco IOS SIP SRST. According to RFC 2543, a SIP registrar is a server that accepts Register requests and is typically collocated with a proxy or redirect server. A SIP registrar may also offer location services.

Note The Cisco IOS Voice Configuration Library includes a standard library preface, glossary, and feature and troubleshooting documents and is located at http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/vcl.htm.

This section contains the following procedures:

• Prerequisites for Configuring the SIP Registrar

• Restrictions for Configuring the SIP Registrar

• Information About Configuring the SIP Registrar

• How to Configure the SIP Registrar

Prerequisites for Configuring the SIP Registrar

Complete the prerequisites documented in the "Prerequisites for Configuring Cisco SIP SRST" section in the "Cisco IOS SIP SRST Feature Overview" chapter.

Restrictions for Configuring the SIP Registrar

See the restrictions documented in the "Restrictions for Configuring Cisco SIP SRST" section in the "Cisco IOS SIP SRST Feature Overview" chapter.

Information About Configuring the SIP Registrar

Cisco SIP SRST provides backup to an external SIP proxy server by providing basic registrar and redirect services. These services are used by a SIP IP phone in the event of a WAN connection outage when the SIP phone is unable to communicate with its primary SIP proxy. The Cisco SIP SRST device also provides PSTN gateway access for placing and receiving PSTN calls.

To make maximum use of the Cisco SIP SRST service, the local SIP IP phones should support dual (concurrent) registration with both their primary SIP proxy or registrar and the Cisco SIP SRST backup registrar. Cisco SIP SRST works for the following types of calls:

•Local SIP IP phone to local SIP phone, if the main proxy is unavailable.

•Additional services like class of restriction (COR) for local SIP IP phones to the outgoing PSTN. For example, to block outgoing 1-900 numbers.

How to Configure the SIP Registrar

This section contains the following procedures:

• Configuring the SIP Registrar (required)

• Configuring Backup Registrar Service to SIP Phones (required)

• Configuring Backup Registrar Service to SIP Phones (Using Optional Commands) (optional)

• Verifying SIP Registrar Configuration (optional)

• Verifying Proxy Dial-Peer Configuration (optional)

Configuring the SIP Registrar

The local SIP gateway that becomes the SIP registrar acts as a backup SIP proxy or redirector and accepts SIP Register messages from SIP phones. It becomes a location database of local SIP IP phones that are set up for dual registration. Dual registration allows SIP IP phones to simultaneously register with both their primary and their fallback registrar devices. That is, when a SIP IP phone registers with a Cisco SIP SRST gateway, it simultaneously registers with the main proxy and SIP redirect server for coverage in case of a WAN failure.

A registrar accepts SIP Register requests and dynamically builds VoIP dial peers, allowing the Cisco IOS voice gateway software to route calls to SIP phones.

If a SIP Register request has a Contact header that includes a DNS address, the Contact header is resolved before the contact is added to the SIP registrar database. This is done because during a WAN failure (and the resulting Cisco SIP SRST functionality), DNS servers may not be available.

SIP registrar functionality is enabled with the following configuration. By default, Cisco SIP SRST is not enabled and cannot accept SIP Register messages. The following configuration must be set up to accept incoming SIP Register messages.

Prerequisites

The SIP endpoints (IP phones) must support dual concurrent registration, which is registering with the main SIP proxy and the Cisco SIP SRST device (redirect server) at the same time. If this requirement is not met, the Cisco SIP SRST device cannot route incoming calls to the SIP phone. For configuration instructions, see the Cisco IP Phone Documentation for Session Initiation Protocol (SIP).

SUMMARY STEPS

1. enable

2. configure terminal

3. voice service voip

4. sip

5. registrar server [expires [max sec] [min sec]]

6. end

DETAILED STEPS


	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	voice service voip Example: Router(config)# voice service voip	Enters voice service configuration mode.
Step 4	sip Example: Router(config-voi-srv)# sip	Enters SIP configuration mode.
Step 5	registrar server [expires [max sec] [min sec]] Example: Router(conf-serv-sip)# registrar server expires max 600 min 60	Enables SIP registrar functionality. The keywords and arguments are defined as follows: •expires: (Optional) Sets the active time for an incoming registration. •max sec: (Optional) Maximum expiration time for a registration, in seconds. The range is from 600 to 86400. The default is 3600. •min sec: (Optional) Minimum expiration time for a registration, in seconds. The range is from 60 to 3600. The default is 60.
Step 6	end Example: Router(conf-serv-sip)# end	Returns to privileged EXEC mode.

What to Do Next

For incoming SIP Register messages to be successfully accepted, users must also set up a voice register pool. See the "Configuring Backup Registrar Service to SIP Phones" section.

Configuring Backup Registrar Service to SIP Phones

Backup registrar service to SIP IP phones can be provided by configuring a voice register pool on SIP gateways. The voice register pool configuration provides registration permission control and can also be used to configure some dial-peer attributes that are applied to the dynamically created VoIP dial peers when SIP phone registrations match the pool. The following call types are supported:

•SIP IP phone to or from

–local PSTN

–local analog FXS phones

–local SIP IP phone (using VoIP-to-VoIP dial-peer redirect)

The commands in the configuration below provide registration permission control and set up a basic voice register pool. The pool gives users control over which registrations are accepted by a Cisco SIP SRST device and which can be rejected. Registrations that match this pool create VoIP SIP dial peers with the dial-peer attributes set to these configurations. Although only the id command is mandatory, this configuration example shows basic functionality.

For command-level information, see the appropriate command page in the Cisco IOS SIP SRST Version 3.4 Command Reference.

Prerequisites

•The SIP registrar must be configured before a voice register pool is set up. See the "Configuring the SIP Registrar" section for complete instructions.

Restrictions

•The id command identifies the individual SIP IP phone or sets of SIP IP phones that are to be configured. Thus, the id command configured in Step 5 is required and must be configured before any other voice register pool commands. When the mac address keyword and argument are used, the IP phone must be in the same subnet as that of the router's LAN interface, such that the phone's MAC address is visible in the router's Address Resolution Protocol (ARP) cache. Once a MAC address is configured for a specific voice register pool, remove the existing MAC address before changing to a new MAC address.

•Proxy dial peers are autogenerated dial peers that route all calls from the PSTN to Cisco SIP SRST. When a SIP phone registers to Cisco SIP SRST and the proxy command is enabled, two dial peers are automatically created. The first dial peer routes to the proxy, and the second (or fallback) dial peer routes to the SIP phone. The same functionality can also be achieved with the appropriate creation of static dial peers (manually creating dial peers that point to the proxy). Proxy dial peers can be monitored to one proxy IP address, only. That is, only one proxy from a voice registration pool can be monitored at a time. If more than one proxy address needs to be monitored, you must manually create and configure additional dial peers.

Note To monitor SIP proxies, the call fallback active command must be configured, as described in Step 3.

SUMMARY STEPS

1. enable

2. configure terminal

3. call fallback active

4. voice register pool tag

5. id {network address mask mask | ip address mask mask | mac address}

6. preference preference-order

7. proxy ip-address [preference value] [monitor probe {icmp-ping | rtr} [alternate-ip-address]]

8. voice-class codec tag

9. application application-name

10. end

DETAILED STEPS


	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	call fallback active Example: Router(config)# call fallback active	Enables a call request to fall back to alternate dial peers in case of network congestion. •This command is useful to monitor the proxy dial peer and fallback to the next preferred dial peer. For full information on the call fallback active command, see the PSTN Fallback Feature.
Step 4	voice register pool tag Example: Router(config)# voice register pool 12	Enters voice register pool configuration mode for SIP phones. •Use this command to control which registrations are accepted or rejected by a Cisco SIP SRST device.
Step 5	id {network address mask mask \| ip address mask mask \| mac address} Example: Router(config-register-pool)# id network 172.16.0.0 mask 255.255.0.0	Explicitly identifies a locally available individual or set of SIP IP phones. The keywords and arguments are defined as follows: •network address mask mask: The network address mask mask keyword/argument combination is used to accept SIP Register messages for the indicated phone numbers from any IP phone within the indicated IP subnet. •ip address mask mask: The ip address mask mask keyword/argument combination is used to identify an individual phone. •mac address: MAC address of a particular Cisco IP phone.
Step 6	preference preference-order Example: Router(config-register-pool)# preference 2	Sets the preference order for the VoIP dial peers to be created. Range is from 0 to 10. Default is 0, which is the highest preference. •The preference must be greater (lower priority) than the preference configured with the preference keyword in the proxy command.
Step 7	proxy ip-address [preference value] [monitor probe {icmp-ping \| rtr} [alternate-ip-address]] Example: `Router(config-register-pool)# proxy 10.2.161.187 preference 1`	Autogenerates additional VoIP dial peers to reach the main SIP proxy whenever a Cisco SIP IP phone registers with a SIP SRST gateway. The keywords and arguments are defined as follows: •ip-address: IP address of the SIP proxy. •preference value: (Optional) Defines the preference of the proxy dial peers that are created. The preference must be less (higher priority) than the preference configured with the preference command. Range is from 0 to 10. The highest preference is 0. There is no default. •monitor probe: (Optional) Enables monitoring of proxy dial peers. •icmp-ping: Enables monitoring of proxy dial peers using ICMP ping. Note The dial peer on which the probe is configured will be excluded from call routing only for outbound calls. Inbound calls can arrive through this dial peer. •rtr: Enables monitoring of proxy dial peers using RTR probes. •alternate-ip-address: (Optional) Enables monitoring of alternate IP addresses other than the proxy address. For example, to monitor a gateway front end to a SIP proxy.
Step 8	voice-class codec tag Example: Router(config-register-pool)# voice-class codec 15	Sets the voice class codec parameters. The tag argument is a codec group number between 1 and 10000.
Step 9	application application-name Example: Router(config-register-pool)# application SIP.App	Selects the session-level application on the VoIP dial peer. Use the application-name argument to define a specific interactive voice response (IVR) application.
Step 10	end Example: Router(config-register-pool)# end	Returns to privileged EXEC mode.

What to Do Next

There are several more voice register pool commands that add functionality, but that are not required. See the "Configuring Backup Registrar Service to SIP Phones (Using Optional Commands)" section for these commands.

Configuring Backup Registrar Service to SIP Phones (Using Optional Commands)

The prior configurations set up a basic voice register pool. The configuration in this procedure adds optional attributes to increase functionality.

Prerequisites

•Prerequisites as described in the "Configuring Backup Registrar Service to SIP Phones" section.

•Configuration of the required commands as described in the "Configuring Backup Registrar Service to SIP Phones" section.

SUMMARY STEPS

1. enable

2. configure terminal

3. voice register pool tag

4. translate-outgoing {called | calling} rule-tag

5. alias tag pattern to target [preference value]

6. cor {incoming | outgoing} cor-list-name {cor-list-number starting-number [- ending-number] | default}

7. incoming called-number [number]

8. max registrations value

9. number tag number-pattern {preference value} [huntstop]

10. dtmf-relay [cisco-rtp] [rtp-nte] [sip-notify]

11. end

DETAILED STEPS


	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	voice register pool tag Example: Router(config)# voice register pool 12	Enters voice register pool configuration mode. •Use this command to control which registrations are accepted or rejected by a Cisco SIP SRST device.
Step 4	translate-outgoing {called \| calling} rule-tag Example: `Router(config-register-pool)# translate-outgoing called 1`	Allows explicit setting of translation rules on the VoIP dial peer to modify a phone number dialed by a Cisco IP phone user. •The rule-tag argument is the reference number of the translation rule. Valid entries are 1 to 2147483647.
Step 5	alias tag pattern to target [preference value] Example: Router(config-register-pool)# alias 1 94... to 91011 preference 8	Allows Cisco SIP IP phones to handle inbound PSTN calls to telephone numbers that are unavailable when the main proxy is not available. The keywords and arguments are defined as follows: •tag: Number from 1 to 5 and the distinguishing factor when there are multiple alias commands. •pattern: The prefix number; matches the incoming telephone number and may include wildcards. •to: Connects the tag number pattern to the alternate number. •target: The target number; an alternate telephone number to route incoming calls to match the number pattern. •preference value: (Optional) Assigns a dial-peer preference value to the alias. The value argument is the value of the associated dial peer, and the range is from 1 to 10. There is no default.
Step 6	cor {incoming \| outgoing} cor-list-name {cor-list-number starting-number [- ending-number] \| default} Example: Router(config-register-pool)# cor incoming call91 1 91011	Configures a class of restriction (COR) on the VoIP dial peers associated with directory numbers. COR specifies which incoming dial peers can use which outgoing dial peers to make a call. Each dial peer can be provisioned with an incoming and outgoing COR list. The keywords and arguments are defined as follows: •incoming: COR list to be used by incoming dial peers. •outgoing: COR list to be used by outgoing dial peers. •cor-list-name: COR list name. •cor-list-number: COR list identifier. The maximum number of COR lists that can be created is four, comprised of incoming or outgoing dial peers. •starting-number: Start of a directory number range, if an ending number is included. Can also be a standalone number. •- : (Optional) Indicator that a full range is configured. •ending-number: (Optional) End of a directory number range. •default: Instructs the router to use an existing default COR list.
Step 7	incoming called-number [number] Example: Router(config-register-pool)# incoming called-number 308	Applies incoming called parameters to dynamically created dial peers. The number argument is optional and indicates a sequence of digits that represent a phone number prefix.
Step 8	number tag number-pattern [preference value] [huntstop] Example: Router(config-register-pool)# number 1 50.. preference 2	Indicates the E.164 phone numbers that the registrar permits to handle the Register message from the Cisco SIP IP phone. The keywords and arguments are defined as follows: •tag: Number from 1 to 10 and the distinguishing factor when there are multiple number commands. •number-pattern: Phone numbers (including wildcards and patterns) that are permitted by the registrar to handle the Register message from the SIP IP phone. •preference value: (Optional) Defines the number list preference order. •huntstop: (Optional) Stops hunting if the dial peer is busy.
Step 9	dtmf-relay [cisco-rtp] [rtp-nte] [sip-notify] Example: Router(config-register-pool)# dtmf-relay rtp-nte	Specifies how a SIP gateway relays dual tone multifrequency (DTMF) tones between telephony interfaces and an IP network. The keywords are defined as follows: •cisco-rtp: (Optional) Forwards DTMF tones by using Real-Time Transport Protocol (RTP) with a Cisco proprietary payload type. •rtp-nte: (Optional) Forwards DTMF tones by using RTP with the Named Telephone Event (NTE) payload type. •sip-notify: (Optional) Forwards DTMF tones using SIP NOTIFY messages.
Step 10	end Example: Router(config-register-pool)# end	Returns to privileged EXEC mode.

Examples

The following partial output from the show running-config command shows that voice register pool 12 is configured to accept all registrations from SIP IP phones with extension number 50xx from the 172.16.0.0/16 network. Autogenerated dial peers for registrations that match pool 12 have attributes configured in this pool.

voice register pool 12

 id network 172.16.0.0 mask 255.255.0.0

 number 1 50.. preference 2

 application SIP.app

 preference 2

 incoming called-number

 cor incoming allowall default

 translate-outgoing called 1

 voice-class codec 1

Verifying SIP Registrar Configuration

To help you troubleshoot a SIP registrar and voice register pool, perform the following steps.

SUMMARY STEPS

1. debug voice register errors

2. debug voice register events

3. show sip-ua status registrar

DETAILED STEPS

Step 1 debug voice register errors

Use this command to debug errors that happen during registration, for example:

Router# debug voice register errors

*Apr 22 11:52:54.523 PDT: VOICE_REG_POOL: Contact doesn't match any pools

*Apr 22 11:52:54.539 PDT: VOICE_REG_POOL: Register request for (33015) from (10.2.152.39)

*Apr 22 11:52:54.539 PDT: VOICE_REG_POOL: Contact doesn't match any pools.

*Apr 22 11:52:54.559 PDT: VOICE_REG_POOL: Register request for (33017) from (10.2.152.39)

*Apr 22 11:53:04.559 PDT: VOICE_REG_POOL: Maximum registration threshold for pool(3) hit

If there are no voice register pools configured for a particular registration request, the message "Contact doesn't match any pools" is displayed.

Step 2 debug voice register events

Using the debug voice register events command should suffice to display registration activity. Registration activity includes matching of pools, registration creation, and automatic creation of dial peers. For more details and error conditions, you can use the debug voice register errors command.

Router# debug voice register events

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: Contact matches pool 1

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: key(91011) contact(192.168.0.2) add to contact 
table

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: key(91011) exists in contact table

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: contact(192.168.0.2) exists in contact table, ref 
updated

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: Created dial-peer entry of type 1

Apr 22 10:50:21.731 PDT: VOICE_REG_POOL: Registration successful for 91011, registration 
id is 257

The phone number 91011 registered successfully, and type 1 is reported in the debug, which means there is a preexisting VoIP dial peer.

Step 3 show sip-ua status registrar

Use this command to display all the SIP endpoints currently registered with the contact address.

Router# show sip-ua status registrar

Line          destination      expires(sec)  contact

============  ===============  ============  ===============

91021         192.168.0.3      227           192.168.0.3

91011         192.168.0.2      176           192.168.0.2

95021         10.2.161.50      419           10.2.161.50

95012         10.2.161.50      419           10.2.161.50

95011         10.2.161.50      420           10.2.161.50

95500         10.2.161.50      420           10.2.161.50

94011         10.2.161.40      128           10.2.161.40

94500         10.2.161.40      129           10.2.161.40

Verifying Proxy Dial-Peer Configuration

To use the icmp-ping keyword with the proxy command to assist in troubleshooting proxy dial peers, perform the following steps.

SUMMARY STEPS

1. configure terminal

2. voice register pool tag

3. proxy ip-address [preference value] [monitor probe {icmp-ping | rtr} [alternate-ip-address]]

4. end

5. show voice register dial-peers

6. show dial-peer voice

DETAILED STEPS

Step 1 configure terminal

Use this command to enter global configuration mode.

Router# configure terminal

Step 2 voice register pool tag

Use this command to enter voice register pool configuration mode.

Router(config)# voice register pool 1

Step 3 proxy ip-address [preference value] [monitor probe {icmp-ping | rtr} [alternate-ip-address]]

Set the proxy command to monitor with icmp-ping:

Router(config-register-pool)# proxy 10.2.161.187 preference 1 monitor probe icmp-ping

Step 4 end

Returns to privileged EXEC mode.

Router(config-register-pool)# end

Step 5 show voice register dial-peers

Use this command to verify dial-peer configurations, and notice that icmp-ping monitoring is set.

Router# show voice register dial-peers

dial-peer voice 40035 voip

preference 5

destination-pattern 91011

redirect ip2ip

session target ipv4:192.168.0.2

session protocol sipv2

voice-class codec 1

dial-peer voice 40036 voip

preference 1

destination-pattern 91011

redirect ip2ip

session target ipv4:10.2.161.187

session protocol sipv2

voice-class codec 1

monitor probe icmp-ping 10.2.161.187

Step 6 show dial-peer voice

Finally, use the show dial-peer voice command on dial peer 40036, and notice the monitor probe status.

Note Also highlighted is the output of the cor and incoming called-number commands.

Router# show dial-peer voice

VoiceOverIpPeer40036

peer type = voice, information type = voice,

description = `',

tag = 40036, destination-pattern = `91011',

answer-address = `', preference=1,

CLID Restriction = None

CLID Network Number = `'

CLID Second Number sent

source carrier-id = `', target carrier-id = `',

source trunk-group-label = `', target trunk-group-label = `',

numbering Type = `unknown'

group = 40036, Admin state is up, Operation state is up,

incoming called-number = `', connections/maximum = 0/unlimited,

! Default output for incoming called-number command

DTMF Relay = disabled,

modem transport = system,

huntstop = disabled,

in bound application associated: 'DEFAULT'

out bound application associated: ''

dnis-map =

permission :both

incoming COR list:maximum capability

! Default output for cor command

outgoing COR list:minimum requirement

! Default output for cor command

Translation profile (Incoming):

Translation profile (Outgoing):

incoming call blocking:

translation-profile = `'

disconnect-cause = `no-service'

advertise 0x40 capacity_update_timer 25 addrFamily 4 oldAddrFamily 4

type = voip, session-target = `ipv4:10.2.161.187',

technology prefix:

settle-call = disabled

ip media DSCP = ef, ip signaling DSCP = af31,

ip video rsvp-none DSCP = af41,ip video rsvp-pass DSCP = af41

ip video rsvp-fail DSCP = af41,

UDP checksum = disabled,

session-protocol = sipv2, session-transport = system,

req-qos = best-effort, acc-qos = best-effort,

req-qos video = best-effort, acc-qos video = best-effort,

req-qos audio def bandwidth = 64, req-qos audio max bandwidth = 0,

req-qos video def bandwidth = 384, req-qos video max bandwidth = 0,

RTP dynamic payload type values: NTE = 101

Cisco: NSE=100, fax=96, fax-ack=97, dtmf=121, fax-relay=122

CAS=123, ClearChan=125, PCM switch over u-law=0,A-law=8

RTP comfort noise payload type = 19

fax rate = voice, payload size = 20 bytes

fax protocol = system

fax-relay ecm enable

fax NSF = 0xAD0051 (default)

codec = g729r8, payload size = 20 bytes,

Media Setting = flow-through (global)

Expect factor = 0, Icpif = 20,

Playout Mode is set to adaptive,

Initial 60 ms, Max 300 ms

Playout-delay Minimum mode is set to default, value 40 ms

Fax nominal 300 ms

Max Redirects = 1, signaling-type = cas,

VAD = enabled, Poor QOV Trap = disabled,

Source Interface = NONE

voice class sip url = system,

voice class sip rel1xx = system,

redirect ip2ip = enabled

monitor probe method: icmp-ping ip address: 10.2.161.187,

Monitored destination reachable

voice class perm tag = `'

Time elapsed since last clearing of voice call statistics never

Connect Time = 0, Charged Units = 0,

Successful Calls = 0, Failed Calls = 0, Incomplete Calls = 0

Accepted Calls = 0, Refused Calls = 0,

Last Disconnect Cause is "",

Last Disconnect Text is "",

Last Setup Time = 0.

What to Do Next

To configure Cisco SIP SRST Version 3.0 features such as redirect mode, see the "Configuring Cisco SIP SRST Version 3.0 Features Using Redirect Mode" chapter.

To configure Cisco SIP SRST Version 3.4 features such as call forwarding or call blocking, see the "Configuring Cisco SIP SRST Version 3.4 Features Using Back-to-Back User Agent Mode" chapter.

Table Of Contents

Configuring the SIP Registrar

Contents

Prerequisites for Configuring the SIP Registrar

Restrictions for Configuring the SIP Registrar

Information About Configuring the SIP Registrar

How to Configure the SIP Registrar

Configuring the SIP Registrar

Prerequisites

SUMMARY STEPS

DETAILED STEPS

What to Do Next

Configuring Backup Registrar Service to SIP Phones

Prerequisites

Restrictions

SUMMARY STEPS

DETAILED STEPS

What to Do Next

Configuring Backup Registrar Service to SIP Phones (Using Optional Commands)

Prerequisites

SUMMARY STEPS

DETAILED STEPS

Examples

Verifying SIP Registrar Configuration

SUMMARY STEPS

DETAILED STEPS

Verifying Proxy Dial-Peer Configuration

SUMMARY STEPS

DETAILED STEPS

What to Do Next