Skype is another protocol used for VoIP calls. If you compare SIP vs Skype you can find the main differences:
- SIP is open and standard protocol, used by many vendors. Skype is proprietary (currently owned by Microsoft) and closed.
- SIP phone is more like ordinary phone. The user have its own telephone number. In Skype you don’t have a number.
- With SIP you can use many providers, different clients, hardware phones. In Skype you can use only Skype client.