Configuring SRST to call only 911 outgoing

[dubrennan]

I have a 4224 configured as an MGCP gateway with call manager that runs SRST. When in SRST mode, I am trying to configure the 4224 to use its FXO port for emergency calling, but I don't want to allow other calls to go out and tie up the line - only 911 or 9911. Any help, pointers, or samples would be greatly appreciated.

[ehaseki]

Hi,

Just make two dial-peer pots configurations for the same FXO interface, to which line is connected for 911. Configuration can be as below:

dial-peer voice 1 pots

destination-pattern 911

port -FXO port number-

dial-peer voice 2 pots

destination-pattern 9911

port -FXO port number-

regards,

Erdem...

[dubrennan]

I tried that, but when the 4224 goes into failover and I dial 911 or 9911, after a few seconds I get a new dialtone... I thought those destination-patterns were basically what are required to get dialtone access to the PSTN (thru an FXO)...

[ehaseki]

Hi,

I do not know why it did not work, because I have tried this while testing SRST, not for 911 but for whole external calls. Do you have any other dial-peer pots configuration for the same FXO port, like:

dial-peer voice -tag number- pots

application mgcpapp

port -same FXO port number-

I am not sure, but if you have configured the same FXO port for MGCP, it may be the problem.

regards,

Erdem...

[jstemke]

I believe if you configure the dial-peer to forward all digits, it should work. It looks like the 911 or 9911 on the dial peer is matching the digits and then stripping them, which gives you the secondary dial tone.

[dubrennan]

Regarding forwarding all digits... If I do this, I would expect the 911 dialing would work, but wouldn't 9911 also get forwarded? That wouldn't go through to the PSTN. I still need to strip that initial 9 without stripping it from someone calling 911. Also, with these settings, wouldn't a user be able to dial any number without the initial 9 and get an outside line. My goal is to only allow 911 and 9911 calls to go out.

[Markus Schneider]

You're right, on the dial-peer with dest-pattern 911 you would need to forward all digits, on the dest 9911, just forward 3 digits (forward-digits 3), which will only forward the 3 right-most digits. Alternatively, you could do prefix 911, so it will strip everything (as you see now), and then dial 911.

[dubrennan]

Thank you for your help. That solved it.