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FAX not working with ATA 186


One of our customer is having Callmanager version 6.1. They have a remote branch with SRST configured gateway and a PRI connection.

They are facing problem of sending and recieving FAX. When they are trying to send fax its reach to the gateway and there is an error message showing on the fax machine " Comm. Error". We have tested with defferent fax machine and ATA adaptor but problem is not getting resolved.  Also we have upgraded the firmware of the ATA adaptor.

Can anybody help me to resolve this issue




Re: FAX not working with ATA 186

Hello Thejas,

I can offer a suggestion that may help, but ultimately, ATA-186 isn't supported for fax.  People use it, but if you have trouble with it, you're on your own.  One of the VG units (VG202, VG204, etc.) is a supported, although more expensive, way to solve the issue.

Often with the ATA-186, the issue is really something you can solve with the fax machine itself.  The fax machine doesn't know it's on an VOIP line.  This is a problem because it really doesn't reliably support transmission rates above 14.4.  If you want it rock solid, you need to crank it down to 9600 bps.  The fax machines will attempt to negotiate the highest speed they can get.  If this is above what the voip line supports, you will experience data loss, and the call will be dropped with a communications error.

Some fax machines do not have the option to turn the max transmission speed down.  Some do.  If your machine doesn't, you'll either need to get a fax machine that does support a manually set speed, get a separate analog line outside the voip solution, or engineer it differently (i.e. in a way that doesn't involve the ATA-186).    

New Member

Re: FAX not working with ATA 186

Dear McGlamry,

Thank you for your respond.

Actually they have the same type of ATA adaptor and FAX machine at there head office and it is working fine there.

So that mean ATA186 over the WAN is not supported ?



Re: FAX not working with ATA 186

Didn't say it won't work. Only that it's not supported...i.e. Cisco isn't going to help you with problems with it.


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