[SR-Users] Registration Failure - IMS

Franz Edler franz.edler at technikum-wien.at
Sun Feb 21 21:00:53 CET 2016

Hi Cristina,

> But I have another problem related to registration process. After REGISTER-
> 401 Unauthorized-REGISTER-200 OK, the IMS client sends the SUBSCRIBE
> message (for the "reg" event package subscription) to the S-CSCF, the latter
> replies with NOTIFY and the client correctly responds with 200 OK. In order to
> be notified on any change of registration state for the client, also the P-CSCF
> sends the SUBSCRIBE message to the S-CSCF, the S-CSCF sends a NOTIFY to
> the proxy but, instead of replying with 200 OK, the P-CSCF replies with 404-
> Not Here (like it doesn't recognize that the recipient of the NOTIFY in the
> Req-URI is the P-CSCF itself).
> Have you ever seen similar issue?

I have now spent some time to reproduce the issue.
First of all: I had to adapt module reg_mod.c in ims_registrar_pcscf, because it containes a hardcoded P-CSCF address:
	str pcscf_uri = str_init("sip:pcscf.ims.smilecoms.com:4060");
which is only valid for smilecoms.
Did you also change that?

Then I got exactly the same problem. I found that the P-CSCF config causes in the part "# Check for Subsequent requests:" a reject " sl_send_reply("404","Not here");"
I have doubts that this is correctly designed and have to dig deeper into the logic of the config-file.
Fact is: the NOTIFY request does not contain a Route header and as it not an ACK it goes straight to the reject.
Maybe any IMS expert can shed some light on this code as shown below:

  	# Check for Subsequent requests:                                 
  	if (has_totag()) {                                               
  		# sequential request withing a dialog should                   
  		# take the path determined by record-routing                   
  		if (loose_route()) {                                           
  			if ($route_uri =~ "sip:mo at .*") {                             
  			if(!isdsturiset()) {                                         
  			# RTP-Relay, if necessary                                    
  		} else {                                                       
  			if ( is_method("ACK") ) {                                    
  				if ( t_check_trans() ) {                                   
  					# no loose-route, but stateful ACK;                      
  					# must be an ACK after a 487                             
  					# or e.g. 404 from upstream server                       
  				} else {                                                   
  					# ACK without matching transaction ... ignore and discard
  			sl_send_reply("404","Not here");                             

BR Franz

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