[Serusers] Call pickup

Tue May 22 07:03:58 CEST 2007

This is a type of call control that you most likely need to go through 
SEMS to do (which is a B2BUA).
You might be able to do in it SER as well, with some trouble. I believe 
it should be possible to use the uac function of tm to inject a message 
in an existing transaction, but I'm not sure.
I suggest you try the semsdev list. You can do quick prototyping there 
in ex. python to understand how to do it and if you really need it 
inside SER, you know how it should work. Use serdev for questions like 
the one below.
g-)

Stefano Blasco wrote:
> Dear all,
> i'm trying to have call pickup with SER (i use ser 0.9.6), i mean i'd
> like to have the capability to pick up a call that is directed to
> another user while the other user telephone is ringing.
> Is there someone that suceeded in this features?
>
> If it is not possible to get this feature by configuriation of ser (i
> mean using already present ser functions), is there someone that can
> suggest how to implemente such features? (for istance with external
> scripts,or with avpops, or using fifo, or writing a new ser module).
>
> Maybe the use of fifo could help, in particular i saw the ctd.sh example
> that is able to iniziate a call for two users using t_uac_dlg fifo
> function. I tryed to use t_uac_dlg to send a CANCEL to a transaction in
> progress (in the 180 ringing status) (taking by hand parameters like
> Call-ID, tag, branch etc.), but it seems that t_uac_dlg is not able to
> interact with the transaction in progress because it creates one
> different transaction. Is it real, or am i wrong?
>
> This is some log for this attempt:
> ################################################################
>
>  1(17187) INFO: fifo_server: command empty
>  1(17187) fifo_get_method: method: 'CANCEL'
>  1(17187) DEBUG: fifo_get_ruri: 'sip:801 at x.x.x'
>  1(17187) DEBUG: fifo_get_nexthop: next hop empty
>  1(17187) fifo_get_headers: headers: To: <sip:801 at x.x.x>
> From: Stefano<sip:803 at x.x.x>;tag=237abc61
> Call-ID: 262a660822777d26
> CSeq: 2 CANCEL
>
>  1(17187) parse_headers: flags=-1
>  1(17187) end of header reached, state=9
>  1(17187) DEBUG: get_hdr_field: <To> [28]; uri=[sip:801 at x.x.x]
>  1(17187) DEBUG: to body [<sip:801 at x.x.x>
> ]
>  1(17187) get_hdr_field: cseq <CSeq>: <2> <CANCEL>
>  1(17187) DEBUG: fifo_uac: parse_headers succeeded
>  1(17187) fifo_get_body: body:
>  1(17187) DEBUG: add_param: tag=237abc61
>  1(17187) end of header reached, state=29
>  1(17187) DEBUG: fifo_uac: EoL -- proceeding to transaction creation
>  1(17187) DEBUG:tm:t_uac: next_hop=<sip:801 at x.x.x>
>  1(17187) DEBUG: mk_proxy: doing DNS lookup...
>  1(17187) get_record: lookup(_sip._udp.x.x.x, 33) failed
>  1(17187) sip_resolvehost: no SRV record found for x.x.x, trying
> 'normal' lookup...
>  1(17187) DEBUG:destroy_avp_list: destroying list (nil)
>  1(17187) DEBUG: dlg2hash: 55633
>  1(17187) DEBUG: add_to_tail_of_timer[4]: 0xb5ba0ac0
>  1(17187) DEBUG: add_to_tail_of_timer[0]: 0xb5ba0ad0
>  1(17187) **** done consume
>  2(17188) SIP Request:
>  2(17188)  method:  <CANCEL>
>  2(17188)  uri:     <sip:801 at x.x.x>
>  2(17188)  version: <SIP/2.0>
>  2(17188) parse_headers: flags=1
>  2(17188) Found param type 232, <branch> = <z9hG4bK159d.9169633.0>; state=16
>  2(17188) end of header reached, state=5
>  2(17188) parse_headers: Via found, flags=1
>  2(17188) parse_headers: this is the first via
>  2(17188) After parse_msg...
>  2(17188) preparing to run routing scripts...
>  2(17188) parse_headers: flags=128
>  2(17188) end of header reached, state=9
>  2(17188) DEBUG: get_hdr_field: <To> [28]; uri=[sip:801 at x.x.x]
>  2(17188) DEBUG: to body [<sip:801 at x.x.x>
> ]
>  2(17188) get_hdr_field: cseq <CSeq>: <2> <CANCEL>
>  2(17188) DEBUG: get_hdr_body : content_length=0
>  2(17188) found end of header
>  2(17188) DEBUG: is_maxfwd_present: max_forwards header not found!
>  2(17188) DEBUG: add_param: tag=237abc61
>  2(17188) end of header reached, state=29
>  2(17188) parse_headers: flags=256
>  2(17188) find_first_route: No Route headers found
>  2(17188) loose_route: There is no Route HF
>  2(17188) is_local(): Realm 'x.x.x' is local
>  2(17188) DEBUG: t_newtran: msg id=9 , global msg id=8 , T on
> entrance=0xffffffff
>  2(17188) parse_headers: flags=-1
>  2(17188) parse_headers: flags=60
>  2(17188) t_lookup_request: start searching: hash=55633, isACK=0
>  2(17188) DEBUG: RFC3261 transaction matching failed
>  2(17188) DEBUG: t_lookup_request: no transaction found
>  2(17188) DBG: trans=0xb5ba1488, callback type 1, id 0 entered
>  2(17188) parse_headers: flags=44
>  2(17188) DEBUG: t_lookupOriginalT: searching on hash entry 55633
>  2(17188) DEBUG: RFC3261 transaction matching failed
>  2(17188) DEBUG: t_lookupOriginalT: no CANCEL matching found!
>  2(17188) DEBUG: t_lookupOriginalT completed
>  2(17188) DEBUG: mk_proxy: doing DNS lookup...
>  2(17188) get_record: lookup(_sip._udp.x.x.x, 33) failed
>  2(17188) sip_resolvehost: no SRV record found for x.x.x, trying
> 'normal' lookup...
>  2(17188) check_via_address(x.x.x.x, x.x.x.x, 0)
>
> ################################################################
>
>
> Another thing, i saw that t_uac_cancel, instead, is able to interact
> with an existing transaction, by sending CANCEL to called and 487 to
> caller (using t_lookup_callid function to get transaction from callid
> and cseq). Does someone think that it is possible to modify t_uac_cancel
> to handle basic pickup functions? (that should be CANCEL for the called
> side and redirect for caller towards pickup user)
>
> This is some log for this case:
> ##################################################################
>
>  1(16115) INFO: fifo_server: command empty
>  1(16115) DEBUG: fifo_uac_cancel: ############### begin ##############
>  1(16115) DEBUG: fifo_uac_cancel: callid="0b29c5266716aa67"
>  1(16115) DEBUG: fifo_uac_cancel: cseq="2"
>  1(16115) created comparable call_id header field: >Call-ID:
> 0b29c5266716aa67
> <
>  1(16115) created comparable cseq header field: >CSeq: 2 INVITE<
>  1(16115) just locked hash index 37328, looking for transactions there:
>  1(16115) we have a match: callid=>>Call-ID: 0b29c5266716aa67
> << cseq=>>CSeq: 2<<
>  1(16115) DEBUG: t_lookup_callid: transaction found.
>  1(16115) DEBUG: fifo_uac_cancel: now calling cancel_uacs
>  1(16115) DEBUG: cancel_branch: sending cancel...
>  1(16115) DEBUG: add_to_tail_of_timer[4]: 0xb5b763f0
>  1(16115) DEBUG: add_to_tail_of_timer[0]: 0xb5b76400
>  1(16115) DEBUG: fifo_uac_cancel: ################ end ##############
>
> ##################################################################
>
>
>
> Thank you very much for your help
> Stefano Blasco
>
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>   