I'm trying to stop using my phone number for registering stuff and was wondering what alternatives would be suitable for forwarding messages and calls since I know about Twilio but it seems to be really bad.
Are you trying to do something programmatic with thousands of calls, or just engineer your own bespoke stuff? Seconding AWS SNS for big things. For small projects things, Google Voice at least used to be free or cheap and let you treat phone communications much more like emails than a standard phone number does.