SIP Trunk Provider

Can anyone recommend a highly reliable SIP trunk provider suitable for a business class system?

I have been using, and I have had problems to say the least. Two or three time in the past 6 months we have had outages. My ISP is great - rock solid. When we are having an outage, I set up a recurring ping to verify that I have solid internet and I always do (I may lose 1 out of 1000 pings), but I have problems on inbound calls to all of my DIDs. They all play a message that the number is not in service!

This is not professional and costs me MONEY on lost leads!

And when the support gets back with me 3 days later they say nothing is wrong. The outages usually last a few hours and are sometimes on and off. I don’t know what to do!!!

I am a user in Colorado, USA.

Thanks in advance

Lots of reviews over at dslreports. Personally, I use vitelity inbound and flowroute outbound.