I have a Snom 300 phone working off Orange (France Telecom) Livebox router. We have dial tone. Our it administrator in the US thinks the audio packets are not getting through the firewall, and maybe the settings from our home VoIP phone are conflicting. We need help in setting up these configurations on the Livebox. VoIP ports of 5060 (UDP) RTP range (15000-15511) must be mapped through firewall and remote phone usage ports 2088 (UDP) and 8081 (TCP) must also be mapped through the firewall. If the other firewall is SIP-aware we need to disable this feature so it works with the basic port forwarding.
Any assistance is greatly appreciated.