3640 router keeping incoming ISDN connections up

[Solarstone]

We have just upgraded a 3640 to IOS 12.2(2)T and noticed that all incoming connections to the PRI are staying up 24/7. When doing showing ISDN active, it states "Seconds Left" as unavailable.

Nothing else has changed aside from the IOS upgrade. The majority of routers dialling in are 1600's and a few 2500's. Is it a feature with this IOS ?

 

[98Converter]

This is something I found on Cisco’s website regarding 12.2…. not sure if it’s relevant??

Caveats
Caveats describe unexpected behavior or defects in Cisco IOS software releases. Severity 1 caveats are the most serious caveats; severity 2 caveats are less serious, and severity 3 and severity 4 caveats are still less serious.

CSCdu51334
Severity: 2
Description: This defect pertains to voice gateways running Cisco IOS Release 12.2T that use the High Density Voice Network Module (NM-HDV). Packet-voice digital signal processors (DSPs) in these gateways may pause indefinitely while displaying the following errors on the console:

%VTSP-3-DSP_TIMEOUT: DSP timeout on event 0x6: DSP ID=0x2: DSP Disc (call mode=0) 00:32:48:

%VTSP-3-DSP_TIMEOUT: DSP timeout on event 0x6: DSP ID=0x1: DSP error stats (call mode=1652392208), chnl info(1, 9, 0), chnl info(1, 10, 1)

This condition is triggered when RTP header-compression (cRTP) is configured on a WAN link between gateways. "Connection trunk" is configured for voice services, and fast-switching is enabled on the interface where cRTP is set. When fast-switched cRTP is configured on a WAN interface, one-way audio occurs shortly after a call begins. Calls that are made to the same trunk and other trunks are affected by the one-way audio condition. All DSPs on the NM-HDV pause with the error message shown above.
Workaround: Avoid using fast-switched cRTP on the WAN interfaces. Either discontinue using cRTP or disable fast-switching on the WAN interface using the following interface configuration command:

no ip route-cache

Process-switched cRTP does not trigger this condition.