Can I use "Direct-inward-dial" on T1 CAS?

[jjia]

Hi,

Cisco press book "Troubleshooting Cisco IP Telephony" page 180, says we can not use the "direct-inward-dial" on T1 CAS interface (under dial-peer voice pots"). "Doing so results in calls being dropped immediately...", but in MGCP protocol with T1 CAS gateway, I configured as the following:

!

dial-peer voice 99910199 pots

application mgcpapp

destination-pattern 9T

incoming called-number .

direct-inward-dial

port 1/0:1

!

Looks there is no call dropping issue. Do I need to have or remove this command on this configuration?

Thanks for your help.

JJ

[pacameron]

The DID function is disabled whrn you run the MGCP feature.

Technically the call is not dropped, you normally just hear silence.

The reson it is not needed is that T1 CAS uses in band tones to pass the DNIS digits, so the router is already expecting to hear the tones come in on the audio channel.

The DID command really applies to interfaces like ISDN where the digits are passed out of band via the D channel

[jjia]

Thanks for your information. It works exactly as you mentioned. So I will remove this command on the configuration.

Thanks again.

JJ

[jaregalado]

Hi Paul,

Following the same logic about T1 CAS and direct-inward-dial command, does the same reasoning apply to H.323 gateways or is this just an MGCP issue ?

Thanks.

[jjia]

We tested in LAB with back to back T1 interfaces configured with T1/CAS, which is configured with H323 protocol, there are two senarios(both configured with E&M Wink and Start signal type)

(1) On the controller T1, if we add "dtmf dnis" option,then we need "Direct-inward-dial" command

(2) On the controller T1, if we did not have the "dtmf dnis" option, then we can not have the above command.

Could someone tell me the reason and functionality of "dtmf dnis" option?

Thanks,

JJ