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On a 2800 Series router that runs Cisco IOS Software Release 12.3(11)YS or later and is configured as a Cisco IOS VoIP gateway, an inbound call to the FXO ports connects but no audio is heard


Core Issue

On a 2800 Series router that is configured as a Cisco IOS  Voice over IP (VoIP) gateway, an inbound call to the Foreign Exchange Office (FXO) ports fails with no audio. This issue is observed when the caller-id enable command is configured on the FXO ports. Neither party can hear one another and this error is shown on the debug level:

mbrd_e1t1_vic_connect: setup failed
flex_dsprm_tdm_xconn: voice-port(0/0/0), dsp_channel(/0/0/0)
mbrd_e1t1_vic_connect: setup failed
flex_dsprm_tdm_xconn: voice-port(0/0/1), dsp_channel(/0/0/0)


This issue is documented in Cisco bug ID CSCse56660. The only possible workaround for this Cisco IOS software release is to disable Caller ID on the FXO ports.

In order to resolve this issue, upgrade the Cisco IOS software release as mentioned in the First Fixed-in Version 12.4(4)XC03, 12.4(07b), 12.4(08a), 12.4(9.17), 12.4(03f), 12.4(10.1)T, 12.4(9)T01, 12.4(6)T04, 12.4(4)T05.

Refer to How to enable the Caller ID (CLID) name delivery feature on Cisco IP phones for inbound PSTN calls on the FXO port for more information on how to enable or disable Caller ID.

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