FYI Twilio has a few guides on how to connect their SIP trunking product to Cisco SBCs:
CUCM: https://twilio-cms-prod.s3.amazonaws.com/documents/InteropGu...
ISR: https://www.twilio.com/docs/sip-trunking/sample-configuratio...
They also have a porting process you can use to migrate your numbers from GV/Bandwidth (or you can just buy a Twilio number for $1).