SIP Phones stay registered with SRST router after CUCM is up.

[banst8801]

Hello everyone,

I have deployed SRST in two branches. Next the details:

ISR 2901: IOS version 15.4(3)M3

Cisco IP Phone 8845: sip 8845_65.10-3-2-16

Cisco IP Phone 8945: sip 9-4-2sr2-2

Cisco IP Phone 7821: sip 78xx.10-3-1-12

HEADQUARTER

CUCM version10.5.2.13900-12

The link between branches and Headquarter is through a VPN.

PROBLEM

When the link to headquarter is down, branch´s phones register with SRST router (everything ok until here).

When the link to headquarter is up, branch´s phones stay registered with SRST router.

I have to reset phones to register back to CUCM.

CONFIGURATION

To config SRST I executed the commands below:

Router(config)# voice service voip

Router(config-voi-srv)# allow-connections sip to sip

Router(config-voi-srv)# sip

Router(config-voi-srv)# registrar server expires max 600 min 60

Router(conf-serv-sip)# bind all source-interface Loopback 1

Router(config)# exit

Router(config)# call fallback active

Router(config)# voice register global

Router(config-register-global)# mode esrst

Router(config-register-global)# max-dn 30

Router(config-register-global)# max-pool 30

Router(config)# voice register pool 2

Router(config-register-pool)# id network 172.20.51.0 mask 255.255.248.0

PACKET CAPTURES:

I also capture some packets from phones when they were registered with SRST router and the CUCM was up.

Apparently the phone send a request to the CUCM server, but only that.(attached)

PD: CUCM IP address 172.20.0.28, IP phone IP address: 172.20.59.34

I hope you can help,

Regards

[Jaime Valencia]

Phones should periodically send the keepalive to the CUCM servers to find out when they're back, you would need to make sure that the message is sent by the phone, and that CUCM receives it, and replies with the ACK message for the phone to go back to CUCM.

[Deepak Rawat]

Can you check the value of Connection Monitor Duration being set at the Device Pool level for these phones. In case if it is blank there then go to Enterprise Parameters and change it to -1 from 120. More information about this setting is below:

This setting defines the time that the Cisco Unified IP Phone monitors its connection to Cisco Unified Communications Manager before it unregisters from SRST and reregisters to Cisco Unified Communications Manager.

To use the configuration for the enterprise parameter, you can enter -1 or leave the field blank. The default value for the enterprise parameter equals 120 seconds.

Change this setting if you need to disable the connection monitor or if you want to extend the connection monitor time. The maximum number of seconds that you can enter in the field equals 2592000.
Tip        When you change the value of the connection monitor duration, it applies only to the device pool that is being updated. All other device pools use the value in their own connection monitor duration fields or use the value that is configured in the enterprise parameter. 

Regards

Deepak

[banst8801]

Hello Deepak,

I´ve changed the value of Connection Monitor Duration with no luck. Phones stay registered with SRST router.

Also I´ve found this:

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCus18070/?referring_site=bugquickviewredir

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCus32216/?referring_site=bugquickviewredir

Apparently is a DNS problem, but I am not sure if this is my case.

Regards,

Esteban