VoIP/SIP service with flexible integration, is there one?

Question

CRM

In our company, a self-written CRM system is used to manage a service similar to SaaS.
I can't find a SIP/VoIP service to:

• embed a dialer widget in our CRM (to call directly from our system)
  
• Android/iOS client
  
• on an incoming call in a mobile application / desktop client, show some information about the client from our API
  

Lord, who knows?

Answer 1

SIP/VoIP and a dialer in our CRM are two different things.
In our taxi, it is done like this: SIP / VoIP itself is Asterisk. Caller from CRM is PortSip www.portsip.com/downloads.html
Works well.