Business Continuity and Disaster Recovery

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1: How does your redundant service architecture work?

We maintain redundant SIP proxies (and will be deploying additional proxies in the future). Currently, our SIP proxies are located in Atlanta, GA and Dallas, TX at: and We front end these servers with DNS SRV capability via: Most IP-PBX systems will adhere to DNS SRV and if your system supports DNS SRV you will only have to register to If your system does not support DNS SRV, you will need to set up two SIP trunks on your device, one for and one for You are able to send/receive calls from either server.

2: How does your inbound DID routing redundancy and failover logic work?

For each DID telephone number in your SIP.US account you are able to specify a Primary SIP trunk, Secondary SIP trunk, and PSTN failover number. This means that we will first attempt to send the incoming call to your Primary SIP trunk (presumably your Primary IP-PBX or ATA), if for some reason there is no response from that destination, we will attempt to send that call to your Secondary SIP trunk (presumably your Secondary IP-PBX or ATA), then if that still fails you have the option of finally routing the call to a PSTN failover number of your choice. You do not have to have a Secondary SIP trunk listed if you wish to use the PSTN failover feature, you can just have a single Primary SIP trunk and a PSTN failover number if you prefer.

3: Do you offer PSTN forwarding? Collapse?

Yes. For each DID telephone number in your SIP.US account, you have the option of turning on PSTN forwarding. When set, we will ignore the primary and secondary trunk assignments and send your call directly to the PSTN number you have set without exception.