Calls in and out of MGC controlled FXO port ring then drop

[jeffrey.girard]

Lab environment

Setup

7960 -> CUCM 8.6 -> MGCP controlled FXO port on 2811 router -> PSTN emulator (another 2811) -> E1 trunk -> Public Router (CME) -. 7960

FXO port is set up to PLAR to the 4 digit extension on the CUCM hosted 7960.

Calls from the 7960 on the CUCM ring to the "Public" 7960 and will continue to ring until answered.  As soon as the call is answered, the call drops on the CUCM 7960.

Calls in the other direction, from the Public 7960 to the CUCM 7960 proceeds to teh FXO port, the FXO port answers and PLARs the call to the 7960 on the CUCM.  The CUCM 7960 rings once, and then drops the call.

Running a debug voice ccapi inout on the MGCP gateway indicates a disconnect cause code of 16 (which indicates normal call clearing)

It acts like its a codec mismatch.....

Its a lab so I can run debugs or provide configs if desired.

[acampbell · Accepted solution]

Hi Jeffrey,

After a wee bit more digging - the fxs port on the PSTN box has battery-reversal by default.

My thought is when the fxo set to connected after the ringing stage the fxs in the PSTN box is

signalling a battery reversal which the fxo is seeing as a clear down.

Can you try turning this off on the PSTN router.

!

voice-port 1/0/0

no battery-reversal

!

Hopefully this will resolve the issue and you can get your calls in both directions

Regards,
Alex.
Please rate useful posts.

[jeffrey.girard]

Alex -

     You got it.

     Calls processing in both directions.

     I really appreciate all your time and effort into this

Jeff

[acampbell]

Jeffrey

Glad its fixed & glad to help

Regards,
Alex.
Please rate useful posts.