We have two 28xx Cisco routers connected with E1 link to PSTN (site A and site B). Each gateway have configured on/off ramp faxing with T.37. We found that when I'm sending fax to any other destination than from A to B or B to A, all works fine.
When I'm sending fax from A to B or B to A, transmition end successfuly, bud received fax has only one white line. Received tiff is same all the time independently on sent page.
There is no slips on E1 and same setup we tested on multiple sites.
After some investigation we found that this is probably bug - there is only one IOS which works - IP Voice, 12.4(12)c. All others (12.4 or 12.4T) works wrongly.
Did someone seen this or is using similar configuration without problems?