Paul Long wrote:
What is the difference between DTMF and MF tones? I've never heard of
MF.
MF (multifrequency) tones are, as far as I can tell, used only for in-band trunk signalling, such as on international circuits (Signalling System No. 5) and between PBXes and COs. They use a combination of two tones from the set of 700, 900, 1100, 1300, 1500, and 1700 Hz. See Recommendation Q.151 for how they're used in SS5 to encode digits and control signals. I've not identified a need for MF signals to be carried over H.32x terminals, but maybe Dale or someone else has.
- It shall be mandatory for all H.323 V2 terminals to promote
interoperability.
Please, Mr. Nilsson or Mr. Toga, correct me if I'm wrong, but I don't believe it can be made mandatory at this time. A newer version of a Recommendation can augment and clarify but cannot constrain previous versions.
But a new version of a recommendation CAN add new mandatory requirements on terminals claiming compliance to that new version. For example, if "X" was optional in Version 1, version 2 could make "X" mandatory for terminals claiming compliance to version 2. Or, if "X" was mandatory in version 1, and version 2 specifies an improved technique "XX", version 2 could require that two version 2 terminals communicating with each other use "XX" instead of "X" even though both implement "X" for backward compatibility with version 1. A new version should always require backward compatibility by continuing to mandate fallback to mechanisms required in previous versions.
-- Toby ___________________________________________________________ Toby Nixon, Program Manager - NetMeeting http://www.microsoft.com/netmeeting Microsoft Corporation, Applications and Internet Client Group, Redmond WA USA +1 (425) 936-2792 Fax: +1 (425) 936-7329 mailto:tnixon@microsoft.com