To put Paul's answer in clearer terms - do NOT do that. Sending offerless Invite's is one thing (an INVITE with no SDP), but sending an SDP offer with no m-lines will almost certainly cause you issues (ie, the request will fail). Even if you think you'll be in a closed environment with all the devices known a priori to support it, someday you may want to connect to other SIP domains and your assumptions will be false. If you want to start a call on-hold, send the offer with the appropriate attributes indicating it (ie, a=sendonly/inactive, or whatever), but don't send SDP with no m-line. In fact even starting it on-hold may be an issue for some folks, so you may be better off sending a normal offer and automatically UPDATE-ing or re-Inviting to put it on hold as soon as the initial transaction completes, fwiw.
But of course as a UAS you should be prepared for SDP with no m-lines and SDP on-hold to start. (it's just the old interop adage - be strict in what you send, and forgiving in what you receive) -hadriel > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sip- > [EMAIL PROTECTED] On Behalf Of Paul Kyzivat > > yes, you are right. > > To my knowledge offers with no media are rarely seen. You may have > difficulty getting UAs to accept it. But in principle it is legal. > > Paul > > [EMAIL PROTECTED] wrote: > > Hi all, > > > > Many thanks for all your replies. > > > > One more query is that what is the difference between invite with bhsdp > and invite with no media. > > > > My understanding of these is that invite with bhsdp is: > > > > INVITE sip:[EMAIL PROTECTED]:12000 SIP/2.0 > > From: > <sip:[EMAIL PROTECTED]>;tag=10773021540708372_local.1210137313755_22_1 > 9 > > To: <sip:[EMAIL PROTECTED]> > > Call-ID: [EMAIL PROTECTED] > > Max-Forwards: 70 > > CSeq: 2 INVITE > > Content-Type: application/sdp > > Content-Length: 171 > > > > v=0 > > o=user 0 0 IN IP4 10.238.115.216 > > s=- > > c=IN IP4 0.0.0.0 > > t=0 0 > > m=audio 10000 RTP/AVP 0 101 > > a=rtpmap:0 pcmu/8000/1 > > a=rtpmap:101 telephone-event/8000/1 > > a=sendonly > > > > And for the invite with no media is : > > > > INVITE sip:[EMAIL PROTECTED]:12000 SIP/2.0 > > From: > <sip:[EMAIL PROTECTED]>;tag=10773021540708372_local.1210137313755_22_1 > 9 > > To: <sip:[EMAIL PROTECTED]> > > Call-ID: [EMAIL PROTECTED] > > Max-Forwards: 70 > > CSeq: 2 INVITE > > Content-Type: application/sdp > > Content-Length: 171 > > > > v=0 > > o=user 0 0 IN IP4 10.238.115.216 > > s=- > > c=IN IP4 0.0.0.0 > > t=0 0 > > a=sendonly > > > > > > > > > > am I correct in my understanding? > > > > Thanks & Regards > > Rajeswari.R > > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 1:39 PM > > To: Routhu, Rajeswari (Cognizant) > > Subject: RE: [Sip-implementors] REG: call hold > > > > Depends if it is after the m line, then it is the attribute of that > > media session... If it is before the m line, it is the attribute of the > > entire session. Attributes are advised to be per media parameter as per > > RFC 3264. > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of > > [EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 12:27 PM > > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; > > Sip-implementors@lists.cs.columbia.edu > > Subject: Re: [Sip-implementors] REG: call hold > > > > > > Hi , > > > > > > > > Thanks very much for the info. The scenario iam trying is such that I > > have to put auser on hold actually not call on hold.I was able to set a > > =inactive in the initial invite and the user was placed on hold by > > remote party. > > > > > > > > Iam raising this query again: > > > > With respect to whether a=inactive/sendonly is for whole sdp or for each > > mediaDescription? > > > > > > > > > > > > Thanks & Regards > > > > Rajeswari.R > > > > > > > > From: Mahipati Deshpande [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 12:16 PM > > To: Ramya Jothi; Routhu, Rajeswari (Cognizant); > > Sip-implementors@lists.cs.columbia.edu > > Subject: Re: [Sip-implementors] REG: call hold > > > > > > > > I don't know practical usage of this, but there is no law that prevents > > you to do it. But I could think one usage - auto-redial feature > > supported by service provider. So you should be prepared for this. > > > > Called party can answer with a=sendonly (i.e. call hold) in its first > > answer. This is a very useful for IVR or in call centers. > > > > > > > > Regards, > > Mahipati Deshpande > > > > > > > > ----- Original Message ---- > > From: Ramya Jothi <[EMAIL PROTECTED]> > > To: Mahipati Deshpande <[EMAIL PROTECTED]>; > > [EMAIL PROTECTED]; Sip-implementors@lists.cs.columbia.edu > > Sent: Wednesday, 7 May, 2008 11:10:47 AM > > Subject: RE: [Sip-implementors] REG: call hold > > > > Hi > > > > > > > > To put a call on hold first it needs to be established if they is no > > communication btw two peers > > > > Then what is the need to put them on hold ? > > > > > > > > -Regards Ramya > > > > > > > > > > > > ________________________________ > > > > From: Mahipati Deshpande [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 10:53 AM > > To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; > > Sip-implementors@lists.cs.columbia.edu > > Subject: Re: [Sip-implementors] REG: call hold > > > > > > > > Its not mandatory that you need to offer with "sendrecv" in initial > > INVITE. > > > > > > > > Regards, > > Mahipati Deshpande > > > > > > > > ----- Original Message ---- > > From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> > > To: [EMAIL PROTECTED]; Sip-implementors@lists.cs.columbia.edu > > Sent: Wednesday, 7 May, 2008 10:41:55 AM > > Subject: Re: [Sip-implementors] REG: call hold > > > > > > Hi Ramya, > > > > I got you. You mean first I should establish a call with the useagent > > from the application. Then I need to send the re-invite to the useragent > > with a =send only .Its just not sending the invite, but also reinvite.Am > > I right? > > > > Thanks & Regards > > Rajeswari.R > > > > > > -----Original Message----- > > From: Ramya Jothi [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 10:25 AM > > To: Routhu, Rajeswari (Cognizant); > > Sip-implementors@lists.cs.columbia.edu > > Subject: RE: [Sip-implementors] REG: call hold > > > > Hi Rajeswari > > > > First the call needs to be established > > Only then u can put it on hold > > > > INVITE a = sendrecv > > A -----------> B > > > > 200OK a = sendrecv > > A <------------ B > > > > ACK > > A ------------> B > > > > The above will establish the call > > Now send an Re-INVITE or UPDATE > > > > Re-INVITE a = sendonly > > A ------------> B > > > > 200OK a = recvonly > > A <----------- B > > ACK > > A -----------> B > > > > > > U can also use inactive > > Pls refer RFC 3264 > > > > -Regards Ramya > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of > > [EMAIL PROTECTED] > > Sent: Wednesday, May 07, 2008 10:10 AM > > To: Sip-implementors@lists.cs.columbia.edu > > Subject: [Sip-implementors] REG: call hold > > > > > > Hi all, > > > > > > > > > > > > I want to connect to a useragent i.e, put him on hold from my > > application. The useragent is not on any call initially .For this iam > > creating an invite request and sending it to the useragent as below: > > > > > > > > INVITE sip:[EMAIL PROTECTED]:12000 SIP/2.0 > > > > From: > > <sip:[EMAIL PROTECTED]>;tag=42215289471803874_local.1210132738140_10 > > _10 > > > > To: <sip:[EMAIL PROTECTED]> > > > > Call-ID: [EMAIL PROTECTED] > > > > Max-Forwards: 70 > > > > CSeq: 2 INVITE > > > > Content-Type: application/sdp > > > > Content-Length: 159 > > > > > > > > v=0 > > > > o=user 0 0 IN IP4 10.238.115.216 > > > > s=- > > > > c=IN IP4 0.0.0.0 > > > > t=0 0 > > > > m=audio 10000 RTP/AVP 0 101 > > > > a=rtpmap:0 pcmu/8000/1 > > > > a=rtpmap:101 telephone-event/8000/1 > > > > > > > > For this the useragent is sending response as: > > > > > > > > SIP/2.0 200 OK > > > > Content-Length: 243 > > > > User-Agent: X-Lite release 1002tx stamp 29712 > > > > Content-Type: application/sdp > > > > Allow: INVITE > > > > Allow: ACK > > > > Allow: CANCEL > > > > Allow: OPTIONS > > > > Allow: BYE > > > > Allow: REFER > > > > Allow: NOTIFY > > > > Allow: MESSAGE > > > > Allow: SUBSCRIBE > > > > Allow: INFO > > > > CSeq: 2 INVITE > > > > Call-ID: [EMAIL PROTECTED] > > > > From: > > <sip:[EMAIL PROTECTED]>;tag=42215289471803874_local.1210132738140_10 > > _10 > > > > To: <sip:[EMAIL PROTECTED]>;tag=3861b74f > > > > Contact: <sip:[EMAIL PROTECTED]:12000> > > > > Via: SIP/2.0/UDP > > 10.238.115.216:5060;branch=z9hG4bK870573921493445;ibmsid=local.121013273 > > 8140_10_10 > > > > > > > > v=0 > > > > o=- 1 2 IN IP4 10.238.115.216 > > > > s=<CounterPath eyeBeam 1.5> > > > > c=IN IP4 10.238.115.216 > > > > t=0 0 > > > > m=audio 12002 RTP/AVP 0 101 > > > > a=fmtp:101 0-15 > > > > a=rtpmap:101 telephone-event/8000 > > > > a=sendrecv > > > > a=x-rtp-session-id:CEAECAD8CCB04812A04FE6D267EEB9A0 > > > > > > > > Iam creating the ACK for the response and sending it back and call got > > established with the server and the useragent. > > > > > > > > Now is it the right procedure to put a useragent on hold. If not please > > suggest me the correct procedure, > > > > > > > > > > > > > > > > Thanks & Regards > > > > Rajeswari.R > > > > > > > > > > > > This e-mail and any files transmitted with it are for the sole use of > > the intended recipient(s) and may contain confidential and privileged > > information. > > If you are not the intended recipient, please contact the sender by > > reply e-mail and destroy all copies of the original message. > > Any unauthorised review, use, disclosure, dissemination, forwarding, > > printing or copying of this email or any action taken in reliance on > > this e-mail is strictly prohibited and may be unlawful. > > > > > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > > This e-mail and any files transmitted with it are for the sole use of > > the intended recipient(s) and may contain confidential and privileged > > information. > > If you are not the intended recipient, please contact the sender by > > reply e-mail and destroy all copies of the original message. > > Any unauthorised review, use, disclosure, dissemination, forwarding, > > printing or copying of this email or any action taken in reliance on > > this e-mail is strictly prohibited and may be unlawful. > > > > > > > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > > > > > > > > > ________________________________ > > > > Explore your hobbies and interests. Click here to begin. > > <http://in.rd.yahoo.com/tagline_groups_6/*http:/in.promos.yahoo.com/grou > > ps/> > > > > > > > > > > > > > > > > ________________________________ > > > > Bollywood, fun, friendship, sports and more. You name it, we have it. > > <http://in.rd.yahoo.com/tagline_groups_1/*http:/in.promos.yahoo.com/grou > > ps/bestofyahoo/> > > > > > > > > This e-mail and any files transmitted with it are for the sole use of > > the intended recipient(s) and may contain confidential and privileged > > information. > > If you are not the intended recipient, please contact the sender by > > reply e-mail and destroy all copies of the original message. > > Any unauthorised review, use, disclosure, dissemination, forwarding, > > printing or copying of this email or any action taken in reliance on > > this e-mail is strictly prohibited and may be unlawful. > > > > > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > > This e-mail and any files transmitted with it are for the sole use of > the intended recipient(s) and may contain confidential and privileged > information. > > If you are not the intended recipient, please contact the sender by > reply e-mail and destroy all copies of the original message. > > Any unauthorised review, use, disclosure, dissemination, forwarding, > printing or copying of this email or any action taken in reliance on this > e-mail is strictly > > prohibited and may be unlawful. > > > > > > > > _______________________________________________ > > Sip-implementors mailing list > > Sip-implementors@lists.cs.columbia.edu > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
