Talk:Q.931

Cause messages (labeled here as "Disconnect Causes") are not defined in Q.931, but in Q.850: Usage of cause and location in the Digital Subscriber Signalling System No. 1 and the Signalling System No. 7 ISDN User Part. Note that although a cause should appear in a DISCONNECT message, that is not the only place that they are used. Whosgonna (talk) 13:31, 21 February 2013 (UTC)

Q.931 is a layer 3 protocol according to ITU-T. Thus, it should not be compared with TCP (Layer 4 protocol). See

Q.931, Section 1.1 itself states: NOTE 2 – Alignment of the functions and protocol with those of OSI network layer is for further study. It would seem fair to point out ways in which it performs some TCP like functions. Whosgonna (talk) 13:43, 21 February 2013 (UTC)

If Q.931 has any counterpart in the Internet, wouldn't it be SIP, not TCP? Both SIP and Q.931 are primarily for controlling the setup of telephone voice calls. Karn (talk) 03:14, 7 June 2008 (UTC)

H.323 is similar to SIP. Q.931 is part of the H.323 stack.