Telfon is used to provide Twilio based VOIP, SMS & Whatsapp service for Twilio users that can make and receive voice calls.
If you don't have a Twilio account open one here: https://www.twilio.com/try-twilio

Telfon Provides:
1) International calls
2) You can perform PSTN calls  
3) Telfon provides calling services to over 80+ countries.
4) You can easily switch between multiple numbers.
5) Recordings of calls
6) Send & Receive SMS
7) Send Broadcast messages
8) Send & Receive Whatsapp messages

You First Require:
1) Twilio account
2) If you plan to make calls internationally then you have to provide special permission on "Voice Geographic Permissions page"
3) SID and Auth token

Terms of Use: https://mytelfon.com/privacy-policy/