It is almost Thanksgiving break and something critical has to come up to give us that healthy dose of bite-your-nails-till-they-bleed stress that we all need, right?
Grant it, a simple feature such as transferring an incoming call to an external number is probably not critical for most; but, in my line of business it is. And now I’m out of time and working extra hard to get this issue resolved before my Thanksgiving vacation. Hmf!
So the problem is this:
Incoming calls come in over a SIP Trunk on an Adtran Netvanta 908e Total Access router and are delivered to an Adtran Netvanta 7100 via a PRI link between the two. When it is after hours, the Netvanta 7100 PBX is setup with an Auto Attendant that greets the caller and transfers the call to an external number if the caller chooses the option from the Option Menu. When the caller presses the menu option to be transferred there is silence on the line for several seconds and the message repeats itself. The Auto Attendant is configured to play the recording again in the event the call fails, and fail it did.
A Debug Voice Summary on both units show the call sent out the PRI on the 7100 over to the 908e and then out the SIP Trunk to the carrier. The debug also shows the call terminated with a “Temporary Failure” message.
As per technical support, the call was terminated by the PRI Trunk on the Netvanta 7100 so the transfer never completes. I contacted the carrier with a call sample and the carrier stated that the calling party (customer cell phone) was the originating number and was not a VoIP number so the call fails due to authentication. I replied back letting them know that the PBX AA is supposed to transfer callers to an outside number. The carrier’s response was that “Perhaps, a valid VoIP Tn should be used as diversion header along with calling Tn… SIP invite message of the call sample indicated that there was no diversion header sent to carrier when the call was sent out either.” I was not sure what that meant in English or what settings on the 7100 I should be looking at.
At that point I realized that technical support would not be resolving my issue promptly 😦 So I pulled out the Netvanta 7100 study guide and found the answer rather quickly by searching the term “diversion” and scrolled down until something interesting caught my eye.
Many SIP Service Providers will reject a call from an unknown number, that is, a number not registered to their switch
– Problems can occur when a user on the NetVanta 7000 forwards their phone to an external number
– When the user locally forwards their phone, the original calling party information will be preserved and sent in the From header of the SIP INVITE back out to the provider’s softswitch
Configure Calling Party (ANI) Match/Substitutions to allow forwarding of calls out a SIP Trunk
– Create an ANI Substitution template to match all numbers
– This will be used to replace the From header on forwarded calls along with all other calls routed out the SIP trunk
Thus, on the 908e that has the SIP Trunk to the carrier VoIP network, I navigate to Voice > Trunk Accounts and select the SIP Trunk. Under the ANI Substitution tab, I entered the following:
Match Template: $
Substitution: The registered 10 digit VoIP phone number
And just like that problem fixed.