XCON: Can't Communicate w/ MTA via French X.25 Network

• Microsoft Exchange Server, version 4.0

SYMPTOMS

If Microsoft Exchange is configured to use a sub address, it cannot communicate with another Microsoft Exchange MTA or any other MTA through the French X.25 network (Transpac). When Exchange accepts an X.25 call, it sends back a Call Accept packet with its own X.121 address.

CAUSE

The CCITT X.25 1988 recommendations state that there are two formats for this packet: Basic and Extended. If the Extended format is used, an Address block is optional and Microsoft Exchange operates successfully. However, the French X.25 network uses the basic format. The problem occurs because the French X.25 network automatically adds the local DTE address. The only time that this problem occurs is when you use a sub address.

Microsoft Exchange fails to communicate over X.25 in France. The Extended format is only used if a specific complementary service is required. The Address block is only used if Call Forwarding is active. Because this service is not requested and the Address block is non-zero, the X.25 network clears the communication with an error code of 4A, which translates into Longer of Address non zero.

STATUS

Microsoft has confirmed this to be a problem in Exchange Server version 4.0. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Product Support Services for more information. the hotfix, customers must be encountering the bug as described above. You must track the customers you send this to and supply them with the next Service Pack when it becomes available.

MORE INFORMATION

The following components have been modified to handle special case for non- standard french X.25 network.

   EMSMTA.EXE
   MTACHECK.EXE
   MMIEXT.DLL
   SAALOG.DLL\**