Lots of options for developers
Twilio appears to be targetted at developers, and has a "TwiML" language to manage your calls. While they have a lot of features available to handle your calls, you do need to be tech-savvy to set this up.
They also offer text message capacility on the numbers, but werent able to enable this for a number I ported in - only on their own numbers.
Not just a phone company but a whole Phone SYSTEM
This is a little complicated. I give it a medium rating for customer service but don't really fault them, it's more a matter of their system having so many options and capabilities and it takes some time and effort to learn and develop what you need. But I give them the top value marks because they offer so much more than even the most advanced services without the advanced price if you work through the details to set it all up right. So they take more work than most regular phone companies but it's because they're more than just a regular phone company too.