auto answer via call-info does not work

[Conor Curran]

OS: Ubuntu 13.04
Package: linphone
Version: 3.5.2-10
Expected: Calls auto answer
Happens: Standard call handling
Reproducible: Always

Server side I'm using Asterisk 10.12.1 on Ubuntu 11 LTS, I have also tried other versions.

Support for this seems to be merged 2010/03/31:
http://web.archiveorange.com/archive/v/M5V96mXoNd4jVFjoF74S

/**Testing dialplan**/
exten => 6686,1,NoOp(Autoanswer- test)
        same => n,SIPAddHeader(Call-Info: answer-after=0)
        same => n,dial(sip/supercoolsippeer,30)

exten => 6685,1,NoOp(Autoanswer- getting desperate here)
        same => n,SIPAddHeader(Call-Info:answer-after=0)
        same => n,SIPAddHeader(Call-Info: answer-after=0)
        same => n,SIPAddHeader(Alert-Info: autoanswer)
        same => n,SIPAddHeader(Alert-Info: ;info=alert-autoanswer)
        same => n,Set(_ALERT_INFO=info=alert-autoanswer)
        same => n,SIPAddHeader(Alert-Info: Ring Answer)
        same => n,SIPAddHeader(Alert-Info: sip:\;info=alert-autoanswer)
        same => n,SIPAddHeader(Call-Info: sip:\;answer-after=0)
        same => n,dial(sip/svc.501,30)

/**linphone output**/
Called as "linphone --verbose -l linphone.log"
[20130518-23:23:39] [message] socket 64.62.153.253:35060: read 1567 bytes
[20130518-23:23:39] [warning] Could not set header: call-info: sip:;answer-after=0
[20130518-23:23:39] [warning] Could not set header: alert-info: sip:;info=alert-autoanswer
[20130518-23:23:39] [warning] Could not set header: alert-info: Ring Answer
[20130518-23:23:39] [warning] Could not set header: alert-info: autoanswer
[20130518-23:23:39] [warning] Could not set header: call-info: answer-after=0
[20130518-23:23:39] [warning] Could not set header: call-info: answer-after=0

/**coreapi/sal_eXosip2.c**/
...
        osip_message_get_call_info(ev->request,0,&call_info);
        if(call_info)
        {
                osip_call_info_to_str(call_info,&tmp);
                if( strstr(tmp,"answer-after=") != NULL)
                {
                        op->auto_answer_asked=TRUE;
                        ms_message("The caller asked to automatically answer the call(Emergency?)\n");
                }
                osip_free(tmp);
        }