Incoming call on FXS port returns DTMF tones

[aaron.banks11]

One would think FXS ports are simple.  I have set up a bunch of FXS port and the first port when called, returns DTMF tones.  The configuration on this port is the same as other ports.  Is there a way to determine if this port is faulty in some way?  Outbound calling works.  On an inbound call as soon as the receiver is picked up, DTMF tones are heard and there is no voice path.

[voip7372]

That sounds like the behavior of an analog DID trunk.  I assume you're using loop start trunks from the telco (POTS or whatever you want to call it, but I refer to it by the technical name...loop start line or loop start trunk).  For an analog DID trunk, when the telco sends a call to the customer, there's a 'wink' and then the telco will send in the DTMF digits for the number being dialed in to the customer and the customer's PBX accepts those digits and then dials internal extension or whatever is associated with those digits on the phone system (PBX).  

I don't know if this has anything at all to do with your problem, but it just reminded me that this is sort of how analog DID trunks work.  

[aaron.banks11]

Yes on the loop start and yes on the internal extension.  The DTMF occurs after the call has been picked up.  So the inbound call works fine in so much as the phone rings and can be picked up.  It's like a robot is calling, you answer the phone and he punches in a bunch of DTMF tones.

The odd thing to me is it occurs on the first port and not on any of the other ports.

[voip7372]

That's odd.  I'd be curious to know if the problem follows the line or if it stays at the port no matter what line is connected to it.  For example, flip-flop the lines connected to the port with the problem and a port that is fine and see if the trouble moves to the other port where you moved that line to.

[aaron.banks11]

We were actually thinking about moving the card to a different slot to see if the problem follows.  If it does, I think it's safe to say - bad port.

[aaron.banks11]

Well the solution was to reboot the router. Go figure.