Released on = May 9, 2006, 5:00 am

Press Release Author = Nicole

Industry = Telecommunications

Press Release Summary = Therefore, the VoiceBlue Lite VoIP GSM gateway is capable of
using the STUN service for checking its 'fake' IP address.

Press Release Body =
Using VoIP gateways behind a NAT firewall with a dynamic IP address (typical of ADSL
connection) usually means checking the NAT firewall IP address whenever the
connection is re-opened. The VoIP gateway behind a NAT firewall uses the public IP
address of the NAT firewall as a so-called 'fake' IP address. The VoIP gateway sends
this 'fake' IP address to a Registrar server while registering or to a SIP proxy
when it sends an INVITE packet. If the NAT firewall IP address is changed, the VoIP
gateway sends the 'fake' IP address in the INVITE packet with a faulty IP address
and the Registrar/SIP proxy replies to the faulty IP address, which means that
communication is not established.
Therefore, the VoiceBlue Lite VoIP GSM gateway is capable of using the STUN service
for checking its 'fake' IP address.
The STUN server responds to the request generated by VoiceBlue Lite and its
response contains the NAT firewall IP address ('fake' IP address). It is necessary
to provide the STUN server IP address and the time of the next STUN request.
VoiceBlue automatically requests for its 'fake' IP address in regular intervals as
defined. The STUN service uses port no. 3478 and so the NAT firewall should open
this port.



Web Site = http://www.2n.cz/voiceblue

Contact Details = 2N Telekomunikace
Modranska 621
Praha 4; 143 01
nicole.cz