Hi Puneet
> Does role of UA as UAC/UAS change on each transaction or it remain intact for
> throughout the session?
Yes, the role of UAC and UAS is per transaction basis. As mentioned in RFC 3261
also:
User Agent Client (UAC): A user agent client is a logical entity
that creates a new request, and then uses the client
transaction state machinery to send it. The role of UAC lasts
only for the duration of that transaction. In other words, if
a piece of software initiates a request, it acts as a UAC for
the duration of that transaction. If it receives a request
later, it assumes the role of a user agent server for the
processing of that transaction.
User Agent Server (UAS): A user agent server is a logical entity
that generates a response to a SIP request. The response
accepts, rejects, or redirects the request. This role lasts
only for the duration of that transaction. In other words, if
a piece of software responds to a request, it acts as a UAS for
the duration of that transaction. If it generates a request
later, it assumes the role of a user agent client for the
processing of that transaction.
Regards
Preksha
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Kumar,
Puneet (Puneet)
Sent: Tuesday, August 07, 2012 8:41 AM
To: Brett Tate; [email protected]
Subject: Re: [Sip-implementors] Query of Session Expire & Refresh.
Thanks Brett,
My doubt was related to who is UAC & UAS.
Say UA-A calls UA-B, then UA-A is UAC & UA-B as UAS.
Then UA-B sends a reINVITE to UA-A, will it make UA-B as UAC now?
Thus:
Does role of UA as UAC/UAS change on each transaction or it remain intact for
throughout the session?
Thanks,
Puneet
-----Original Message-----
From: Brett Tate [mailto:[email protected]]
Sent: Monday, August 06, 2012 9:40 PM
To: Kumar, Puneet (Puneet); [email protected]
Subject: RE: Query of Session Expire & Refresh.
> As seen above UA-A calls UA-B. For this call UAC i.e. UA-A will behave
> as a session refresher.
>
> After sometime UA-B sends a reINVITE with Session-Expire header having
> refresher=uac.
> So will it make UA-B as refresher?
Yes; however it ultimately depends upon the value within the re-INVITE's 2xx
response. See RFC 4028 section 9.
> Does the refresher remain intact on the dialog basis or Transaction
> basis ?
The refresher can be renegotiated. See RFC 4028 section 7.4.
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