[asterisk-biz] SIP , SIP-I and SIP-T

[Alex Balashov]

Dome Charoenyost wrote:

> Can someone explain about SIP,SIP-T and SIP-T ?
> and Asterisk support SIP-I,SIP-T or not ?

It is a way to map and/or encapsulate some values particular to PSTN 
signaling protocols (such as ISUP) back into SIP so that SIP can serve 
as a minimally viable transport between two nodes that speak those 
protocols, i.e.

    ISUP ----> SIP/ISUP gateway ----> IP ----> SIP/ISUP gateway ---> ISUP

Asterisk does not really support these because it is a back-to-back user 
agent, so it does not need to follow RFC rules regarding conservation of 
special headers or data elements in a transaction the way that a proxy 
does.  Asterisk can and will regenerate new call legs scoped to the 
interface technologies it actually supports and cares about.

-- 
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
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