Synchronizing Multiple SIP Accounts per IMS Specification

You can enable synchronization between multiple Accounts according to the IMS specification.

The first Account (lowest index number) that is configured for the IMS specification (see procedure below) is considered the "primary" Account. All other Accounts that are configured for the IMS specification are considered as "secondary" Accounts. All the Accounts must have the same Serving IP Group. Up to 99 "secondary" Accounts are supported.

Synchronization between Accounts mainly concerns the registrar server that is used by the Accounts. All Accounts send all associated requests (SIP REGISTERS for the Accounts themselves, and calls matched to the Accounts) to the same single server. The "primary" Account determines the server to use.

Only the "primary" Account does the full "By IMS Specification" registration process. It triggers DNS-resolution of the Proxy Set of the Serving IP Group if the Proxy Set is configured with an FQDN host. It also attempts to register to each of the resolved registrar servers (IP addresses) of the Proxy Set, until it succeeds.

Once the "primary" Account succeeds in registering to a server, the "secondary" Accounts that are enabled for registration ('Register' parameter configured to Regular), register to this same server (and do not attempt to register to any other server). If the "primary" Account is not registered, the "secondary" Accounts can't send REGISTER requests (unless they were already registered prior to the "primary" Account's failure; then they may continue working with the last server as long as it accepts their refresh REGISTERs).

If the "primary" Account registers to a new server (e.g., it was registered to the first address in the Proxy Set and because registration refresh subsequently failed, it registered to the second address in the Proxy Set), the "secondary" Accounts then automatically register to this new server.

Registration failures of "secondary" Accounts trigger the "primary" Account to do an immediate refresh registration. (Only if the refresh REGISTERs of the "primary" Account fail, does the "primary" Account start the full registration process.)

Triggers for immediate refresh registrations, as mandated by the IMS specification (e.g., triggered by failure of outgoing INVITE) are handled normally by "secondary" Accounts that are enabled for registration. "Secondary" Accounts that are disabled for registration ('Register' parameter configured to No), forward the trigger to the "primary" Account, and the "primary" Account sends a refresh REGISTER instead of them.

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To enable synchronization of multiple Accounts per IMS:

Enable the feature by configuring the [SyncIMSAccounts] global parameter to 1.

In the Accounts table, configure all the Accounts for synchronization per IMS with the following settings:

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'Registrar Search Mode': By IMS Specification

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'Serving IP Group': <same IP Group>