The figure below demonstrates a scenario where SIP is used in the Ribbon IP core with minimum routing configuration. The figure also depicts a parallel Gateway and SIP core.

Figure 1: Network Supporting SIP in the Ribbon IP Core


The basic configuration steps to use SIP in the core with minimum routing configuration are shown below.
(for detailed PSX configuration information, please see the PSX Provisioning Guide).

  1. Create a SIP Signaling Port (sipSigPort) and a named SIP Trunk Group (sipTrunkGroup) in the default Address Context (default) and default Signaling Zone (defaultSigZone) for ingress and egress SBCs.

  2. Set the Call Routing useRouteSet received flag for default SIP Trunk Groups.

  3. From the SBC, set signaling "skipDTGLookupForRouteHdr" on the ingress Trunk Group of both Gateways (SBCs) and on the default Trunk Groups (see SIP Trunk Group - Signaling - CLI).

  4. Provision SBCs default SIP Signaling Port address in PSXs Gateway entity. 

    Note

    For SBC SWe N:1 S-SBC deployments, in which a cluster of up to 4 SBC nodes can be active at the same time, the PSX allows the gateway entity to be configured as an FQDN instead of a single IP address to represent the group of nodes collectively. Each of the SBC nodes in the N:1 cluster share a homogenous configuration and register with the PSX using the same common gateway name. When the core SBC sends a Diameter request to the PSX for routing, the PSX returns the gateway FQDN if the S-SBC cluster is the next hop. The core SBC does a DNS lookup to resolve the FQDN to the individual IP addresses of the active nodes within the cluster. For subsequent call requests, the core SBC load balances among the active nodes using a round robin method to rotate among the individual IP addresses. 

  5. Create PSXs Signaling Gateway Groups and associate to ingress and egress SBCs Gateway entities. For using different IP Signaling Profiles (IPSP) based on the direction of the call, create an Inter Signaling Gateway Group.
    1. Set “Use SIP in Core” flag in Inter-Gateway Signaling Group or Signaling Gateway Group IPSP used for the inter-SBC leg.

  6. Set “Destination Trunk Group Options as Include DTG” in PSXs Signaling Gateway Group or the Inter Gateway Signaling Group, IPSP. The ingress SBC inserts the egress Trunk Group of the egress SBC as the Destination Trunk Group (DTG) in the Request URI of the INIVITE. The egress SBC sends DTG to PSX for performing a light weight policy dip.

  7. Set “Originating Trunk Group Options as Include OTG” in PSXs Signaling Gateway Group or the Inter Gateway Signaling Group, IPSP. The ingress SBC inserts the ingress Trunk Group as the Originating Trunk Group (OTG) in the From Header of the INIVITE. The egress SBC sends OTG to PSX, PSX uses OTG as the ingress TG, ingress SBC as the ingress SBC for the light weight policy dip.

  8. Set “Insert Peer Address As Top Route Header” in PSXs Signaling Gateway Group or the Inter Gateway Signaling Group, IPSP. The ingress SBC inserts IP Peer information in the top Route Header of the Invite. The egress SBC sends the IP Peer information from the Route Header to PSX for PSX to return PSP and IPSP associated with the peer.

  9. Set “Use SIP in Core” in PSXs ingress and egress IPSPs for SIP to be used in the Ribbon IP core.

The Ingress IPSP is used for ingress leg, Inter Gateway Signaling Group or Signaling Gateway Group IPSP is used for the inter-SBC leg, and the egress IPSP is used for the egress leg. Similar logic applies for the Packet Service Profiles (PSP).

The following is an example SIP INVITE sent in a SIP-enabled Ribbon IP core:

INVITE sip:9786148389;phone-context=private@10.7.15.250:5060;user=phone;dtg=TG_AS SIP/2.0
Via: SIP/2.0/UDP 10.7.15.146:5060;branch=z9hG4bK00B000781cf6dbe40ae
From: "Unavailable" <sip:Restricted@10.7.15.146;otg=TG_IAD>;tag=gK00000701
To: <sip:9786148389@10.7.15.250;user=phone>
Call-ID: 4_133140212@10.7.15.146
CSeq: 574375236 INVITE
Max-Forwards: 70
Allow: INVITE,ACK,CANCEL,BYE,REGISTER,REFER,INFO,SUBSCRIBE,NOTIFY,PRACK,UPDATE,OPTIONS,MESSAGE,PUBLISH
Accept: application/sdp, application/isup, application/dtmf, application/dtmf-relay, multipart/mixed
Contact: "Unavailable" <sip:Restricted@10.7.15.146.5060>
P-Preferred-Identity: <sip+16031234567@10.7.15.146.5060;user=phone>
Route: <sip:10.7.6.40:10107;lr>
Supported: timer,100rel,precondition,replaces
Session-Expires: 1800
Min-SE: 1800
Content-Length: 187
Content-Disposition: session; handling=required
Content-Type: application/sdp
v=0
o=Sonus_UAC 1833275753 1505414074 IN IP4 10.7.15.146
s=SIP Media Capabilities
c=IN IP4 10.7.15.145
t=0 0
m=audio 1028 RTP/AVP 8
a=rtmap:8 PCMA/8000
a=sendrecv
a=maxptime:10
, msgLen = 1100.