It really depends on what you mean by "good". Like most things, you can have 2 of the 3: cheap, high quality, and reliability. I used teliax for a while and i

It really depends on what you mean by "good". Like most things, you can have 2 of the 3: cheap, high quality, and reliability. I used teliax for a while and it worked out really well for what I needed. For outbound, I use voipjet.com to keep costs down. Ultimately, it will come down to the quality of your server, installation, and QoS on the network. For enterprise quality, you need to start looking at level3 and those types of companies.