16 Aug
2016
16 Aug
'16
12:42 a.m.
Dear All,
I just have a basic SIP question on re-invite. I wonder if "ACK" is required in
a re-invite scenario, like re-invite -> 200 OK -> ACK. What I've seen is for
some reason, my PSTN doesn't send a "ACK" back to me after my 200 OK
response to their re-invite. I don't know if not sending an ACK in a re-invite is an
allowed behavior. Thanks.
Regards,Jay
16 Aug
16 Aug
12:45 a.m.
On 08/15/2016 05:42 PM, Jay Li wrote:
Dear All,
I just have a basic SIP question on re-invite. I wonder if "ACK" is
required in a re-invite scenario, like re-invite -> 200 OK -> ACK. What
I've seen is for some reason, my PSTN doesn't send a "ACK" back to me
after my 200 OK response to their re-invite. I don't know if not sending
an ACK in a re-invite is an allowed behavior. Thanks.
Yes, an ACK is required. Per RFC 3261 § 14.1 ("UAC behavior"):
The rules for transmitting a re-INVITE and for
generating an ACK for a 2xx response to re-INVITE are
the same as for the initial INVITE (Section 13.2.1).
--
Alex Balashov | Principal | Evariste Systems LLC
1447 Peachtree Street NE, Suite 700
Atlanta, GA 30309
United States
Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
1:33 a.m.
Hi Alex,
Thanks for the quick response. I don't have much experience with SIP. I just wonder if
you've seen PSTN providers not send an ACK back to a re-invite? With your professional
experience, is this common? Thanks.
Regards,Jay
On Monday, August 15, 2016 5:46 PM, Alex Balashov <abalashov(a)evaristesys.com>
wrote:
On 08/15/2016 05:42 PM, Jay Li wrote:
Dear All,
I just have a basic SIP question on re-invite. I wonder if "ACK" is
required in a re-invite scenario, like re-invite -> 200 OK -> ACK. What
I've seen is for some reason, my PSTN doesn't send a "ACK" back to me
after my 200 OK response to their re-invite. I don't know if not sending
an ACK in a re-invite is an allowed behavior. Thanks.
Yes, an ACK is required. Per RFC 3261 § 14.1 ("UAC behavior"):
The rules for transmitting a re-INVITE and for
generating an ACK for a 2xx response to re-INVITE are
the same as for the initial INVITE (Section 13.2.1).
--
Alex Balashov | Principal | Evariste Systems LLC
1447 Peachtree Street NE, Suite 700
Atlanta, GA 30309
United States
Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
_______________________________________________
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
sr-users(a)lists.sip-router.org
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
1:34 a.m.
On 08/15/2016 06:33 PM, Jay Li wrote:
Thanks for the quick response. I don't have much
experience with SIP.
I just wonder if you've seen PSTN providers not send an ACK back to
a re-invite? With your professional experience, is this common?
Thanks.
Certainly, not sending end-to-end ACKs for 2xx responses is a problem
that occurs, both for initial and in-dialog invites (reinvites).
However, it indicates that something is misconfigured or improperly
implemented somewhere, and is a serious issue that needs to be addressed.
--
Alex Balashov | Principal | Evariste Systems LLC
1447 Peachtree Street NE, Suite 700
Atlanta, GA 30309
United States
Tel: +1-800-250-5920 (toll-free) / +1-678-954-0671 (direct)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
3021
days inactive
3021
days old
3 comments
2 participants
participants (2)
-
Alex Balashov -
Jay Li