B. Firewall Configurations

Ports used:

In order to communicate with the telephone system, the end devices must be able to communicate outbound via the following ports:

   

Protocol          Target port          Purposes                                   Targets
TCP80, 83, 443, 18443      Provisioningall networks
UDP123NTPall networks
UDP53DNSCustomer DNS server
UDPall portsSIP, RTP, T-38, FMC, etc.109.68.96.0/21
TCPall portsSIP/TLS, SIP, FMC109.68.96.0/21

 

 

ICMP packets type 3 (Destination unreachable) may not be blocked under any circumstances! Otherwise the dynamic determination of necessary transmission parameters may fail at network level.


Filtering and blocking of ICMP packets should be done very carefully, since elementary network operation functionalities may be disrupted.