How can I forward calls from a Twilio or Nexmo number I bought to my Android phone over data / VOIP?

I don't want to forward to my mobile number, I want to install some kind of "softphone" and have Twilio / Nexmo forward the call to that softphone. Can my Android phone receive VOIP calls directly somehow?

This seems like such a simple thing to do, but I can't figure out how to do it. Do I need my own "SIP trunk"? Surely not, for such a simple use-case.

Solution

Twilio developer evangelist here.

You can do this using an Android SIP soft phone (see this post for some recommendations) and Twilio's SIP Registration. Check out the gif below for how to set up SIP registration for incoming calls to a soft phone:

The steps are:

Create a SIP domain in the Twilio console
Create a Credential List with at least one username and password
Enable SIP registration for the SIP domain using the credential list you created
Configure your SIP Phone application
- User the username and password you chose for your credential list
- Make sure the soft phone registers successfully
Buy a number
Configure a TwiML Bin to <Dial> to your <Sip> address on incoming calls
Dial that number and your soft phone should ring

Let me know if that helps at all.