VaxVoIP WebPhone SDK includes sample code in different development tools. You can dial and receive phone calls through any SIP based server, gateway or ITSP (Internet Telephony Service Provider). Activate SIP based video conference. Add SIP based Instant Messaging and Presence feature to your VaxVoIP integrated Webphone. VaxVoIP WebPhone SDK is friendly to those WebPhone clients who are behind the NAT/firewalls.