Outgoing fax failing from VG 202

[puneet.nagar1]

We have a HCS customer who is having an Issue with One way fax on VG202 - they are able to receive fax but are unable to send it.
The issue they are experiencing is that they can receive faxes but not send them. An analogue phone handset was connected to this line and receives a dial tone but cannot call out.
The extension is 65115 and shows up in the CUCDM portal on port number is 0/1 and Line Class of Service is National24Hrs-Standard.

What  is the call flow from CUCM perspective when FAX are in picture ?

How does the FAX get integrated with CUCM ?

What information is required to troubleshoot this ?

Any assistance on this would be appreciated.

[Aseem Anand]

Hi Puneet,

Thanks for reaching out to us. Please find my comments below:

Q. What  is the call flow from CUCM perspective when FAX are in picture ?

A. Call Flow depends on the type of integration whether the VG is added as SCCP, MGCP or with SIP trunk. 

In HCS normally, i have seen partners deploying SIP trunk between VG and the CUCM.

Call Flow becomes:

FXS port >>>> VG 202/204/224 >>>> SIP dial-peer >>>> CUCM >>>> SIP trunk >>>> Provider/SBC

Q. How does the FAX get integrated with CUCM ?

A. Fax gets integrated using the FXS port. Since you are using a VG 202, on VG you will create a SIP dial-peer pointing to CUCM and on CUCM you will have route patterns configured to allow the calls to go out. The type of calls the Analog device can make depends on the CSS specified on the SIP trunk.

Q. What information is required to troubleshoot this ?

A. Since the inbound calls are working fine and only the outbound calls are failing we need to check the following:

(a). Make sure the calls from VG 202 are reaching CUCM. You need to check if you have dial-peers configured which have session target pointing to CUCM.

(b). Collect the following debugs:

sh run

debug voice ccapi inout

debug ccsip messages

(c). Run a DNA on CUCM and make sure the trunk has the necessary priveleges to dial out.

Regards,

Aseem Anand

[Scott Pedersen]

Sounds like you have an outgoing dial-peer issue. Verify your dial peers are configured correctly with the needed destination patterns, correct protocols, and pointing to the correct cucm server group(might be DNS srv tag depending on IOS).

Thanks.