I’ve been reselling for Calltower/Appia even before the merger. The trunks are very reliable, and there’s only been a few hickups due to the ISP’s being at fault. I manage over a dozen businesses that have Calltower as their provider.
I am using just basic SIP trunking, and I handle all the PBX operations on my side.
Pricing is very good on what is delivered for the cost. I fortunately have some good reps I can deal with to get things going.
A few customers have had billing issues, such as 2 trunks that needed to be invoiced to one owner was messed up for a few months, and a trunk that needed to transfer ownership proved a huge challenge.
Once it’s set up and rolling correctly, Outages and service interruption are pretty darn rare. Getting things rolling can be a bit of an adventure, HOWEVER, the tech team always speaks English, and I don’t have to deep dive into proving that I represent the customers before we can get something done.
Tech team gets an A-
Billing Team gets a C.