New subject: What is a good strategy to build Kamailio <--> pbx

16 Aug 2020

What are  your thoughts on  architecture  build of the  following scenarios.

The PBX doesn’t  support websockets and we want to use sip.js / jsSip.  (use Kama as
wss:// SIP proxy)
PBX has direct PRI/sip Trunks/ DID control/ Voicemail.
PBX hosts SIP extensions.

UA --> Kamailio --> PBX

--------SCENARIO A.)  ------- Host SIP[xxxx] extensions on  Kama box  but same SIP
extensions  are also on PBX [xxxx]

  1.  Build some sort of control to register handle  kama to pbx …. (but reg  webclients)

Kama [1100]  SIP-PBX [1100]

Does kama act as the UA 1100  / registered   to PBX

What about UA to kamailio (do we do 1100a so UA-kama is 1100a)  but  kama  is  maintain 
REG/status/  but  passing that IF client  is  online  ?

MWI (voicemail is hosted on PBX)  so how does that move through can it.

------- SCENARIO  B.) ------  Proxy all/ everything . use route[REGFW] Forward all REG to 
PBX..

Issues  ----
MWI  (SIP notify  ?)
SIP Incoming CALL  incoming calls  to  work.  (if UA holds REG to outbound proxy on PBX 
or )
DTMF (sipINFO) doesn’t work (I see it sending)
I noticed I crashed the PBX because all the SIP scanners started pounding my  Kamailio box
after 2 days when  I added route[REGFW] it starting eating up SIP trunk channels on PBX 
cause started forwarding everything.  Like it starting 4241(a)xxxxx.com 4242(a)xxxxx.com  .

Or  might need to look at fail2ban  pike module  to oget this but still  had issues I just
don’t know where to look or code to fix on SCENARIO B

Snippets on  my testing .

    route[REGFWD] {
                        if(!is_method("REGISTER"))
                        {
                        return;
                        }

        $var(rip) = $sel(cfg_get.PBX.bindip);
        $uac_req(method)="REGISTER";
        $uac_req(ruri)="sip:" + $var(rip) + ":" +
$sel(cfg_get.PBX.bindport);
        $uac_req(furi)="sip:" + $au + "@" + $var(rip);
        $uac_req(turi)="sip:" + $au + "@" + "kamaproxy";
        # $uac_req(turi)="sip:" + $au + "@" + $var(rip);
        $uac_req(hdrs)="Contact: <sip:" + $au + "@"
                                                + $sel(cfg_get.kamailio.bindip)
                                                + ":" +
$sel(cfg_get.kamailio.bindport) + ">\r\n";
        if($sel(contact.expires) != $null)
                        $uac_req(hdrs)= $uac_req(hdrs) + "Expires: " +
$sel(contact.expires) + "\r\n";
                        else
                        $uac_req(hdrs)= $uac_req(hdrs) + "Expires: " +
$hdr(Expires) + "\r\n";
                        uac_req_send();
                        }
        #!endif

---------------

So this led me to extra security   should  I host SIP extensions on kamailio as an extra
security but then what about  MWI/inbound then) or do I have 1100 on kama which mitel is
1100  but I pass all info from inbound.