cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements

Secondary dial tone heard on inwards calls from PSTN with T1 CAS MGCP gateway

2416
Views
0
Helpful
0
Comments

Core Issue

Cisco IOS  Software based voice gateway runs Media Gateway Control Protocol (MGCP) for VoIP signaling control between the gateway and Cisco CallManager. External callers hear a period of secondary dial tone for inwards calls, specifically Public Switched Telephone Network (PSTN) towards Cisco CallManager. After this burst of dial tone, the call proceeds as expected: the IP phone rings and the external caller hears an in-band ringback.

This is the configuration for the customer's voice gateway router:

!
controller T1 1/0
  framing esf
  linecode b8zs
  ds0-group 1 timeslots 1-24 type e&m-wink-start dtmf dnis
!
!
dial-peer voice 11 pots
  application mgcpapp
  port 3/0:1
!

Resolution

To resolve this issue, perform these steps:

  1. Change the voice gateway router configuration by removing the keywords dtmf  dnis for the ds0-group T1 controller command.

    The new configuration would be as follows:

    ! 
    controller T1 1/0
      framing esf
      linecode b8zs
      ds0-group 1 timeslots 1-24 type e&m-wink-start
    !
    
  2. After the config changes have been made, re-register the gateway to the Cisco CallManager by issuing the no mgcp | mgcp config command.

CreatePlease to create content
Content for Community-Ad
August's Community Spotlight Awards