MCP with fractional E1

[carlsclan]

we have a 2821 configured as a MGCP GW on CCM 4.1(3). The gateway during normal operation does not facilitate the in or outbound calls - another GW off site does, however when in SRST it should, but when calls are placed - only an engaged tone is heard.

I have had problems in the past using a fractional E1 (only 16 channels in use) and have had to use H323 instead. Any one had similar problems and ways to solve the issue?

cheers.

[paolo bevilacqua]

Are you using ISDN PRI ?

Can you better describe the problem and post router config ?

[carlsclan]

hi chaps,

ISDN PRI - yes. Problem is that when a call is placed from an IP phone they get the busy tone.

I dont get anything out of the ISDN Q931 debugs, so it looks as if the call is not being placed to the controller.

[pcobley · Accepted solution]

What does a debug isdn q931 show on the gateway ?

If it shows requested circuit or channel unavailable then I suspect you need to change the channel selection order in the gateway config page.

Paul.

[s.zink]

Hi,

I had a similar problem.

Fractional PRI is not supportet with mgcp yet.

When you use srst the router will go out on the higher pri channel.

Possible you can experimente with this:

-Under the D channel, enter the following command:

isdn bchan-number-order ?

ascending

descending

Sebastian