Strange Problem with Outgoing Faxes Over SIP

[sheldoom]

I have a customer IP500v2, Release 9.1.100.10, that has about 30 very-heavy traffic fax machines, connected to analog ports on the IPO, call out over SIP trunks. Incoming faxes are working fine. Outgoing faxes are working fine, unless an outgoing fax receives a busy signal, it appears that the fax machine does not actually receive a busy message from telco initiating the redial functionality of the fax machine. So, the fax that just failed because the far-end machine was busy, is now stuck in the fax machine queue and does not redial and stays there until someone clears it.

Has anyone seem this problem before?

"All men are fools. Some the wise, fool others. Others the foolish fool themselves. While a rare few fool both others and themselves. These are the rulers of men" from 'The Darkness That Comes Before' by R Scott Bakker

 

[amriddle01]

If you plug in with a test butt do you hear busy signal? That's all the fax listens for there is no other messaging on that side of things.
Fax and SIP are not the best bed follows anyway, are you sure it's the busy signal issue and not baud rate causing the issue?

 

[sheldoom]

WE have tweaked the baud rate. Avaya recommended lowering it to 9600 this was done and there seemed to be some improvement. I can get a tech to site to test. Internal faxes seem to work every time. The issue seems to be only with outgoing calls over the SIP trunks.

"All men are fools. Some the wise, fool others. Others the foolish fool themselves. While a rare few fool both others and themselves. These are the rulers of men" from 'The Darkness That Comes Before' by R Scott Bakker

 

[intrigrant]

Sounds like the Fax machines don't recognize the busy signal of the analog port, try this:
Make a call between to internal phones and then send a fax to on of the two busy stations.
If the fax still redials when calling a busy station then it is the fax to blaim and not the SIP trunk.
See if you can get specs of the fax about the parameters it use to detect a busy number and compare it with IP Office parameters, I bet they are not compatible.