I've just cutover a Cisco CM solution last week for a client. They have a Canon fax machine that has been working flawlessly on ther Avaya Magix system for years. Now, the Canon fax machine hooked up to an FXS port configured as MGCP. The link to the PSTN is a PRI configured as H323. The fax machine is used as outbound only. It can fax successfully to many numbers. However, a certain number does not work and the fax fails. Of course, this is one of there most commonly used numbers. If we hook up an analog phone and dial that same number, the calls connects and fax tones are heard. If we connect it back to the fax machine and listen to the tones, we hear some tones that I've never heard before and the call drops. We've hooked this up to an analog line and the fax succeeds...so that tells me something is needed on the Cisco side. We even tried a different fax machine to the same number and the other side got the document, but it was shrunk to a very small size. The configuration for the router/GW is attached.