Do you meet voip bloking problem?
YES!!!
So you need VGCP.

VGCP (Voice Guard@ Control Protocol) is our core technology for VoIP anti-blocking solutions. It is a proprietary layer 2 link protocol working at between IP stack and NIC driver. The core patent-pending VGCP is industry’s most state-of-the-art voice service provider class security protocol whose scalability and flexibility results in not to compromise voice quality and overhead. VGCP controls and monitors full voice signaling and media flow intelligently, meanwhile disguise SIP and RTP packets into normal allowed data packets such as DNS and TFTP, and makes two-way encryption and decryption driven by user-customized policy. Even in some circumstance, VGCP can simulate traffic behavior of universal data networking protocol such as OICQ, MSN and so on.

Key Features
 Maximum call completion rate and maximum voice service duration
 SIP core standards and variety of drafts supported
 Proprietary link layer protocol for controlling
 Any 3rd-party softphone / ATA/ Gateway / IP Phone / IAD and SIP proxy / Registrar / SBC supported
 The most comprehensive codec including G711 / G.729ab / iLBC / GSM / speechX supported
 Bypassing Narus and Verso platform detection
 Flexible user-customized encryption policy driven
 Strict call path protection and security up to termination
 Only simultaneous signaling / media / T.38 fax packet support across any firewall
 No network of firewall modification is required
 Excellent voice quality without any latency and performance compromise
 Small footprint terminal SDK
 Available on all major platforms

Technical Specification
Support UDP, TCP, RTP / RTCP, T.38 Fax, SIP – RTC3261~3266, STUN-RFC3489, Symmetric Response-RFC3581, DNS / TFTP / Radius wrapper

VGCP Family Components
 VGBC (Voice Guard@ Border Controller)
 VoiceGuard@ SDk for softphone / ATA / Gateway / IAD / IP Phone (available on Windows, Embedded Linux)
 VoiceGuard@ Plug-in (VG Plug-in) for Windows & Linux
 VoiceGuard Standalone Client(VGSC) for Windows
 VGSPE VoIP Security Phone adapter

For more details pls refer to SpeedVoIP - Professional VoIP Anti-Blocking Solution or sales@speed-voip.com

Homepage:SpeedVoIP - Professional VoIP Anti-Blocking Solution
Email:sales@speed-voip.com
MSN:svoipsales@hotmail.com