- Bronze, 100 points or more
I have a strange problem that I was hoping somebody out there may have a creative solution for. The vast majority of our installations are done in remote locations where hardline DSL or Cable are unavailable. Therefore, we use both Satellite and Cellular to provide data connectivity. Satellite is the most reliable and we are able to control this connection on a granular level as well as provide our clients with an SLA on service. Cellular is anybody's guess, but sometimes it works great and other times it does not.
Most of our clients want the ability to load balance between satellite and cellular and we have employed the SA520 for this purpose, but I'm running into a problem with the SIP trunk registration. Again, due to the nature of our client's work, these systems are usually dormant (and shut down) until needed. At that time, everything gets powered up including satellite and cellular, but it takes a mere number of minutes for the cellular to come up and online whereas the satellite takes closer to 10 minutes to complete the connection. On a typical startup, the SA520 will look at both WAN ports and perform a DNS lookup on the DNS servers supplied by each connection. Satellite appears to be down, even though it is still coming online, whereas Cellular responds much more quickly. The SA520 routes all traffic through the Cellular connection, and the UC540 registers with the SIP trunk provider via the cellular connection. In the next few minutes, the satellite connection comes up and the SA520 begins routing traffic through this port via the RTP and SIP protocol bindings that I have set in the SA520 for this traffic.
Now this is where I'm scratching my head. The SIP trunk provider has a static IP for incoming calls (the SA520 WAN interface for the satellite modem). But because the UC540 has already registered SIP via the cellular WAN port on the SA520, incoming calls are getting denied. If I manually unregister the UC540 and tell it to register (once the satellite connection is up), incoming calls work again. I thought that I found a solution by setting the reregistration time very low (60 second), but the SIP provider complains (understandably) that they are being bombarded by register requests. Their recommendation is to remove the registrar server completely, but this also seems to break my incoming calls.
Has anybody run into anything like this or have a creative solution? Anything to check or try?
Thanks in advance,