XFOR: MTA can't Communicate with Another MTA via French X.25

• Microsoft Exchange Server, version 4.0

SYMPTOMS

If Microsoft Exchange is configured to use a sub address, it can't communicate with another Microsoft Exchange Message Transfer Agent (MTA) or any other MTA through the French X.25 network (Transpac). When Microsoft 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 will operate successfully. However, the French X.25 network uses the Basic format. The problem occurs since 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.

MORE INFORMATION

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. Since 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 Microsoft Exchange Server version 4.0. This problem was corrected in the latest Microsoft Exchange Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

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