NRS Collaborative Server

Introduction

Collaborative servers is a way to provide VoIP trunking between PBX's when each PBX has it's own NRS domain and a network path to the other NRS domain(s). NRS Manager provides a utility for adding and viewing Collaborative Servers:

If the gateway sends a call to the local NRS domain for endpoint resolution, but no match is found, the gateway will next query the Collaborative Server NRS domain(s).

• When a routing match is found, the NRS returns the appropriate endpoint IP address.
  - The gateway initiates a peer-to-peer (TLAN) connection between endpoints, and the call proceeds.
• If no routing match is found in any NRS domain, the call fails and the caller hears reorder (fast busy).

With multiple sites/endpoints, the TLAN networks must be fully meshed (Single-Hop connectivity to all endpoints). An ELAN path is not required. Note, in Releases 6.0 and earlier, calls through the collaborative servers could only be made in the same domain.

When Collaborative Servers are running different versions of CS1000 software, NRS features are limited to the capabilities of the earliest NRS software version.

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Programming:

At PBX-A:

• Use CDP to send the PBX-B DN range to the SIP trunk route.
  - If the dialing plan(s) are compatible, send the CDP to the SIP trunk RLI.
  - If the dialing plan(s) are NOT compatible, choose a prefix and adjust the FLEN accordingly.
    Build an RLI with a suitable DMI (to remove the prefix) as needed.

  Note: the entire dialed string is queried in the NRS, even if the prefix is deleted in the RLI later.
  Therefore, enter the prefix in the NRS, even if it doesn't appear to be sent to the route.

• Enter the Node IP (TLAN) of PBX-B in the PBX-A NRS as a 'Collaborative NRS'.

At PBX-B:

• In PBX-B's NRS, select "endpoints' and add a routing entry on the relevant endpoint.
  - If the dialing plan(s) are compatible, this may already exist.
  - If you are using a prefix, add the prefix code as a routing entry.

At both PBX's:

• In Element Manager, check the NODE SIP URI Map settings are compatible.
  - Check the Private UDP/CDP domain names are the same on both PBX's.

If you want two-way dialing, also repeat these steps on the other PBX.

Notes:

• Check that each PBX can Ping the Node, NRS, and endpoint IP addresses of the other (TLAN).
• Remember the networks must be fully meshed, so that every endpoint see's every other endpoint.
• VPN tunnels should be "nailed-up" to prevent rejected calls if the tunnels drop or go to sleep.
• I've only got this working with SIP, and prior to Rel. 6 the domain names must match.

The idea is, a DN is dialed on PBX-A and sent out on the IP trunks - so asking PBX-A's NRS for an endpoint address.
PBX-A's NRS has no entry, so it passes the request on to its 'Collaborative NRS' friend, which happens to be PBX-B.
PBX-B resolves the endpoint, gives PBX-A the endpoint IP address, and the call is set up.

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