This document remedies the situation where calls to most locations work, but calls to mobile (cell) phones or international locations fail. These calls typically disconnect with "recovery on timer expiry" in the Cisco IOS® Q.931 debugs.
There are no specific requirements for this document.
The information in this document is based on Cisco CallManager 3.x and 4.x.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
For more information on document conventions, refer to the Cisco Technical Tips Conventions.
Mobile Telephony networks typically take longer to connect, since they have to locate the user. International calls also typically experience delays in call establishment. This causes the timer T310 to expire.
This timer is initiated when Call Proceeding is received and stopped when Alert, Connect, Disc, or Progress is received. It is easy to determine if this is the issue by looking at debugs and/or Cisco CallManager traces. In order to do that, locate the Call Proceeding and verify that the Disconnect is sent n seconds later for every call that fails. You can verify that n is the value set for the T310 timer. This value is typically 10 seconds.
This is sample output from the debug isdn q931 command on an IOS gateway.
Feb 4 11:10:40.396: ISDN Se3/0:15: TX -> SETUP pd = 8 callref = 0x000E
Feb 4 11:10:40.396: Bearer Capability i = 0x8090A3
Feb 4 11:10:40.396: Channel ID i = 0xA9838F
Feb 4 11:10:40.396: Display i = 'John', 0x20, 'Smith'
Feb 4 11:10:40.396: Calling Party Number i = 0x0080, '123456', Plan:Unknown, Type:Unknown
Feb 4 11:10:40.396: Called Party Number i = 0x80, '654321', Plan:Unknown, Type:Unknown
Feb 4 11:10:40.432: ISDN Se3/0:15: RX <- SETUP_ACK pd = 8 callref = 0x800E
Feb 4 11:10:40.432: Channel ID i = 0xA9838F
Feb 4 11:10:42.508: ISDN Se3/0:15: RX <- CALL_PROC pd = 8 callref = 0x800E
Feb 4 11:10:42.508: Progress Ind i = 0x8288 - In-band info or appropriate now available
Feb 4 11:10:42.508: Progress Ind i = 0x8282 - Destination address is non-ISDN
Feb 4 11:10:50.492: ISDN Se3/0:15: TX -> DISCONNECT pd = 8 callref = 0x000E
Feb 4 11:10:50.492: Cause i = 0x80E6 - Recovery on timer expiry
Feb 4 11:10:50.548: ISDN Se3/0:15: RX <- RELEASE pd = 8 callref = 0x800E
Feb 4 11:10:50.552: ISDN Se3/0:15: TX -> RELEASE_COMP pd = 8 callref = 0x000E
In order to solve this situation, increase the value of timer T310. This can be done on the Cisco CallManager or the IOS gateway. When the call is controlled by the Cisco CallManager (in particular, if a Skinny Call Control Protocol (SCCP) gateway is used), this action needs to be carried out following Solution 1: Cisco CallManager Configuration. If no Cisco CallManager is involved (in particular, if you operate in Survivable Remote Site Telephony (SRST) mode), this action needs to be carried out following Solution 2: IOS Configuration.
Complete these steps.
From the Cisco CallManager Administration page, select Service > Service Parameters.
Select Cisco CallManager from the list on the left if you use Cisco CallManager 3.x or select Cisco CallManager from the Service drop-down box if you use Cisco CallManager 4.x.
Cisco CallManager version 3.x
Cisco CallManager version 4.x
On the Service Parameters Configuration page, look for T310.
Set the value of T310 Timer (msec) to the recommended value of 60000 msec.
Scroll to the top of the page and click Update.
IOS configuration is achieved through this interface command:
Router(config-if)#isdn t310 <value in milliseconds>
You can check the setting using the show isdn timers command.
Router#show isdn timers
ISDN Serial2/0:15 Timers (dsl 0) Switchtype = primary-net5
ISDN Layer 2 values
K = 7 outstanding I-frames
N200 = 3 max number of retransmits
T200 = 1.000 seconds
T202 = 2.000 seconds
T203 = 10.000 seconds
ISDN Layer 3 values
T303 = 4.000 seconds
T304 = 30.000 seconds
T305 = 30.000 seconds
T306 = 30.000 seconds
T307 = 180.000 seconds
T308 = 4.000 seconds
T310 = 60.000 seconds
T313 = 4.000 seconds
T316 = 120.000 seconds
Note: In Cisco CallManager version 3.x, due to operator implementations in some countries, you can be required to include a "sending complete indicator". This parameter is located in the Cisco CallManager parameters page.
Note: By default, in Cisco CallManager version 4.x, all outbound calls through a PRI interface that use an ETSI-based protocol type include sending a complete indicator in the outgoing SETUP message. This indicates effectively that all these outbound calls use Enbloc signaling, not overlap sending procedures for call setup. Due to operator implementations in some countries, it can possibly be required to enable overlap sending. In order to do this, check the Allow Overlap Sending check box in the Route Pattern configuration page.