I am presently looking at integrating with one of the telephony providers. I am trialing Aircall but I was wondering if any other the other providers have an even tighter integration? Which provider's integration is the gold standard?

My main query is about how to assign a incoming / outgoing call from a number which is not in CRM. Is there anyway to capture this (either with Aircall or another provider) and add this to the contact record? For example, if a customer calls us from an unknown number, how do we save this?