Reference:Configuration/IP/Settings

The basic IP settings are made here.

TOS

The TOS (Type of Service) byte inside the IP header is used for prioritization of packets inside the network. The device allows some packets to be marked as higher priority. The TOS values for this purpose are configured here.

TOS Priority RTP-Data	Configuration of the TOS value for media (e.g. voice) packets. The value 0x10 is used as standard. Consequently, voice data receives priority forwarding.
TOS Priority Signaling	Configuration of the TOS value for Signaling (e.g. H.323 or SIP) packets.

RTP Port Range

First UDP RTP port / numbers of port: This entry restricts the range of ports in which UDP RTP voice data (User Datagram Protocol Real-time Transport Protocol) is received for H.323 or SIP calls. The port range 16384 to 32767 is used as standard.

Range calculation: 4 * <estimated-number-of-simultaneous-calls> but at least 128.

Note: For every single VoIP connection 4 ports are allocated. One (even) RTP port, one (odd) RTCP port, one (even) T.38 port. The fourth port is not used but lost, since the next call's RTP port must be an even port again. This information applies to all kind of devices, even such devices that do not support T.38 fax (telephones).

Restrictions: 128 ports are the smallest range.

UDP NAT Port Range

First UDP NAT port / numbers of port: This entry restricts the range of ports that may use UDP NAT data (Network Address Translation).

Related Articels

Howto:What Ports are used for Signaling and Voice Traffic in SIP and H.323?