Subject: RE: [Sip] Need guidance in call transfer - SIP Based

From: "Umesh Sharma" <[email-masked]>
Date: Wed, 22 Sep 2004 09:53:46 +0530

pls see inline.
-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of
Anurag Kabra (by way of Anurag Kabra<[email-masked]>) (by way of
Anurag Kabra <[email-masked]>)
Sent: Monday, September 20, 2004 1:24 PM
To: [email-masked]
Subject: [Sip] Need guidance in call transfer - SIP Based

I am currently working on VoIP, and I am located in India.
 I have few queries which are bothering me, could you suggest me something
on
 them.  Below are my queries.

1. Do we do retransmission for Refer Request(& Notify) if it doesnot reach
transferee.
>> timeout/retransmission mechanism for refer is same as for bye, non-invite
transactions; when notify times out it is not retransmitted & correp.
subscription should be removed.

2. In a unattended call transfer, when does the dialog end i.e. normally
with a
BYE or Notify(subscriptio-state="terminated").
3. Does the dialog exists even after BYE or subscription-state header in
Notify will terminate the dialog.

2, 3>> my understanding from rfc 3265 bye would not terminate the dialog if
there is subscription on it, subscriber-state="terminated" destroys the
subscription and the dialog if no other application state is associated with
the dialog (more in 3.3.4 rfc 3265). For Call transfer refer goes with in
existing dialog.

4. Is 202 Accepted sent after getting a REFER request, ignored by the
transferor. What is the effect of the response 202 Accepted?
>> it indicates that the subscription has been accepted and that
authorization to proceed with transfer may or may not have been granted.
Also, that a notify will be sent immediately (3.1.4.1). It also creates a
new dialog & subscription if the initial refer was not sent on a
pre-existing dialog otherwise it just creates the new subscription with the
dialog.

This is all for now.  Hope to hear from you soon. Thanks in advance.

Best Regards
 Anurag.

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_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip