I've been using didlogic.com for this for many years.
Their web UI makes it really easy to set up round-robin and to to turn destinations on/off. This is really useful for me as I can easily change the set of destination numbers with just a few taps, when I land somewhere.
interesting idea, but why would i use this over Twilio? yea, i know i would need to do some tweaking to Twilio to get it to do the same as this, but it would actually work out cheaper on their end, i think...
Twilio is great if you have someone to set it all up. If you are a small company or a freelancer, than twilio might not be the simplest solution. With conumber you don't need to setup anything. Choose a city and tell us where we should forward the incoming calls to. Takes 1 minute and you're ready.