The following is an excerpt from H.225 V3: 7.17 Message Not Understood This message is sent whenever an H.323 endpoint receives a RAS message it does not understand. RequestSeqNum - Shall be the requestSeqNum of the unknown message, if it can be decoded, and zero otherwise. But in the ASN.1 included, the range for the request sequence number is: Requestseqnum ::= INTEGER (1..65535) With my latest version of the OSS compiler, I get a constraint violation attempting to send a zero request identifier. Is zero still the correct value when unable to decode a received PDU? Mike Michael Ely mely@paknetx.com http:\\www.paknetx.com