Re: [Sip-implementors] Precondition is added into 200OK re-INVITE
On 4/18/19 8:00 PM, anhright wrote: Hi Paul, My concern is not about fax machine, it is about my system when it receives re-INVITE with no precondition, but it adds precondition to the 200 OK. Putting them in does no harm. But it may indicate problems if it expects something to happen as a result. Thanks, Paul Thanks, A.C Sent from my Samsung Galaxy smartphone. Original message From: Paul Kyzivat Date: 4/18/19 23:21 (GMT+07:00) To: sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip-implementors] Precondition is added into 200OK re-INVITE On 4/17/19 10:50 PM, Anh Cao wrote: > Hi all, > > I meet a weird case with precondition but can not find any document talk > about it: > > I make SIP call from my system to the fax machine. In the initial INVITE, > my system includes precondition in Supported header and status in SDP. But > fax machine does not support precondition so it removes precondition from > Supported header and status from SDP. > > After voice call is established, fax machine sends T.38 re-INVITE to my > system to start fax with Supported header has no precondition and SDP has > no status. > And my system answers fax machine by 200 OK with Supported has precondition > and T.38 SDP has status for precondition: > m=image 55314 udptl t38 > a=T38FaxVersion:0 > a=T38MaxBitRate:14400 > a=curr:qos local sendrecv > a=curr:qos remote sendrecv > a=des:qos none local sendrecv > a=des:qos none remote sendrecv > > Is it the acceptable behavior? and there is any document talk a bout this > case? with re-INVITE for voice all and for fax call, the behaviors are the > same or different? I don't see anything wrong with this. The "Supported" is declaring your *support* for preconditions. The fax machine is acting as it should given that it doesn't support or understand preconditions. It is apparently ignoring the a= lines carrying precondition status, which is what an implementation is supposed to do with attributes it doesn't understand. What else do you think should be done? This is basic behavior for extensions. Thanks, Paul ___ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors ___ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
Re: [Sip-implementors] Precondition is added into 200OK re-INVITE
Hi Paul,My concern is not about fax machine, it is about my system when it receives re-INVITE with no precondition, but it adds precondition to the 200 OK.Thanks,A.CSent from my Samsung Galaxy smartphone. Original message From: Paul Kyzivat Date: 4/18/19 23:21 (GMT+07:00) To: sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip-implementors] Precondition is added into 200OK re-INVITE On 4/17/19 10:50 PM, Anh Cao wrote:> Hi all,> > I meet a weird case with precondition but can not find any document talk> about it:> > I make SIP call from my system to the fax machine. In the initial INVITE,> my system includes precondition in Supported header and status in SDP. But> fax machine does not support precondition so it removes precondition from> Supported header and status from SDP.> > After voice call is established, fax machine sends T.38 re-INVITE to my> system to start fax with Supported header has no precondition and SDP has> no status.> And my system answers fax machine by 200 OK with Supported has precondition> and T.38 SDP has status for precondition:> m=image 55314 udptl t38> a=T38FaxVersion:0> a=T38MaxBitRate:14400> a=curr:qos local sen drecv> a=curr:qos remote sendrecv> a=des:qos none local sendrecv> a=des:qos none remote sendrecv> > Is it the acceptable behavior? and there is any document talk a bout this> case? with re-INVITE for voice all and for fax call, the behaviors are the> same or different?I don't see anything wrong with this. The "Supported" is declaring your *support* for preconditions. The fax machine is acting as it should given that it doesn't support or understand preconditions. It is apparently ignoring the a= lines carrying precondition status, which is what an implementation is supposed to do with attributes it doesn't understand.What else do you think should be done?This is basic behavior for extensions. Thanks, Paul___Sip-implementors mailing listsip-implement...@lists.cs.columbia.eduhttps://lists.cs.columbia.edu/mailman/listinfo/sip-implementors ___ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
Re: [Sip-implementors] Precondition is added into 200OK re-INVITE
On 4/17/19 10:50 PM, Anh Cao wrote: Hi all, I meet a weird case with precondition but can not find any document talk about it: I make SIP call from my system to the fax machine. In the initial INVITE, my system includes precondition in Supported header and status in SDP. But fax machine does not support precondition so it removes precondition from Supported header and status from SDP. After voice call is established, fax machine sends T.38 re-INVITE to my system to start fax with Supported header has no precondition and SDP has no status. And my system answers fax machine by 200 OK with Supported has precondition and T.38 SDP has status for precondition: m=image 55314 udptl t38 a=T38FaxVersion:0 a=T38MaxBitRate:14400 a=curr:qos local sendrecv a=curr:qos remote sendrecv a=des:qos none local sendrecv a=des:qos none remote sendrecv Is it the acceptable behavior? and there is any document talk a bout this case? with re-INVITE for voice all and for fax call, the behaviors are the same or different? I don't see anything wrong with this. The "Supported" is declaring your *support* for preconditions. The fax machine is acting as it should given that it doesn't support or understand preconditions. It is apparently ignoring the a= lines carrying precondition status, which is what an implementation is supposed to do with attributes it doesn't understand. What else do you think should be done? This is basic behavior for extensions. Thanks, Paul ___ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
[Sip-implementors] Precondition is added into 200OK re-INVITE
Hi all, I meet a weird case with precondition but can not find any document talk about it: I make SIP call from my system to the fax machine. In the initial INVITE, my system includes precondition in Supported header and status in SDP. But fax machine does not support precondition so it removes precondition from Supported header and status from SDP. After voice call is established, fax machine sends T.38 re-INVITE to my system to start fax with Supported header has no precondition and SDP has no status. And my system answers fax machine by 200 OK with Supported has precondition and T.38 SDP has status for precondition: m=image 55314 udptl t38 a=T38FaxVersion:0 a=T38MaxBitRate:14400 a=curr:qos local sendrecv a=curr:qos remote sendrecv a=des:qos none local sendrecv a=des:qos none remote sendrecv Is it the acceptable behavior? and there is any document talk a bout this case? with re-INVITE for voice all and for fax call, the behaviors are the same or different? I really appreciate your advice Thanks and regards, A.C ___ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
