I've just reported two bugs on libss7's MTP2 implementation related with lost messages (losing MSUs without sending them and missing the need to request retransmissions) If you're seeing lots of: 2010-10-30 13:44:23.896 SS7: Got retransmission request sequence numbers greater than 89. Retransmitting 1 message(s). 2010-10-30 13:44:23.896 SS7: Len = 12 [ 98 db 09 85 80 00 18 52 25 00 10 00 ] 2010-10-30 13:44:23.896 SS7: FSN: 91 FIB 1 (notice that we're being asked to send greater than 89 and we send 91) followed by a T7 expired and link go down, https://issues.asterisk.org/view.php?id=18392 could help you. https://issues.asterisk.org/view.php?id=18393 is a bit harder to see if it's biting you, because it's hidden on links with much activity and when it happens you'll only see the link going down by the remote side (on a T7) Hope it helps, -- Horacio J. Pe?a horape at compendium.com.ar horape at uninet.edu