SIP Trunk Providers

We’re looking for a SIP trunking provider that meets several criteria. I’ve looked around and haven’t found exactly what we’re looking for. Maybe that’s because I haven’t been looking hard enough, and maybe it’s just because it isn’t there. We are currently using as our trunk provider. Their service is great, but they dont’ have the feature set we’re looking for.

We are going to host IP PBX systems for our clients so a company with a good wholesale/partner program would be benificial.
We need to support E911 (basic feature, I’m sure)
We would prefer if the trunk used registrations (so that our PBX can be behind the NAT, and is more easily failed over on a new IP in the event of an internet outage. Our current provider doesn’t use registrations, we create the trunk and open port 5060 to their IP and they send calls directly to our PBX)
We need to support IP failover (our PBX can register from more than one single IP. In the event of an internet outage, we would register out a second IP. Our current provider will only send calls to a single IP and to change it requires manualy updating your account with them)
Having a pricing plan that includes unlimited minutes on a trunk would be nice. Some of our clients will be high call volume and we don’t want to shoulder that liability if we are charging them a flat rate per user (which is probably how the model will be setup).

That’s pretty much it. Does anyone know of a trunk provider that fits these criteria? We’re currently using and like their pricing and such, but they don’t use registrations, and as I said before, their failover support is nonexistent. If we are going to be providing service for our clients we can’t host them on a system that isn’t setup for redundancy.

Any recommendations would be great! Thanks!

I personally use I believe they have all the features you are looking for.