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New Member

FXS Ports Fax Machine

Hi All,

I am having trouble with a fax machine connected to a fxs ports in a voice gateway.

The fax machine looks to be able to send faxes ok, but when an incomming call is received it rings onces then bascally hangs up.

From a "debug isdn q931" I can see a "user busy" error message is sent back to the caller.

When calling from an IP phone a "sh voice port sum" only show the call as connecing it never actually connects the call.

I have tried setting the fxs port as both sccp and mgcp, but symptions (?) are the same for both.

Any ideas on where to look nect would be greatly appreciated.




Re: FXS Ports Fax Machine

Hi Jason,

It is very likely that your port isn't registered with MGCP or SCCP, or you aren't matching the dial peer correctly.

Do a 'debug voip dialpeer' and place an outgoing call. Check the incoming call and see if it has 'service mgcpapp' or 'service stcapp' on it. You're likely using SIP/H323 for outgoing calls and don't realize it.


New Member

Re: FXS Ports Fax Machine

Thanks Nick,

It turn out there is a know issue with the VIC2-FXS card and using RJ11 cables that have 4 wires.  After replacing the 4 wire cable with a 2 wire cable the issue went away.

Below is the link with the issue..