ATL Telecom IP300S - Manual (Page 87)

IP SIP Phone v2 User’s Guide Mar. 2005
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„ The network administrator has mapped 7 consecutive UDP ports, 45700 ~ 5706,
from NAT to your terminal, which the terminal IP is 192.168.3.57.
Note 1: Since the network administrator has to configure the NAT/firewall to map
those UDP ports to your terminal statically, thus you should use static IP instead of
DHCP as your network configuration. Otherwise you take the risk that the ATA
would get a different IP from the currently set into the mapping when it reboot and
re-get its IP by DHCP.
Note 2: If there are several terminals reside under the same NAT, their NAT port
mappings must not be overlapped since they all share the same NAT resource!
z Configure RTP ports
„ RTP Port Base: 45700 (Must be an even number and between 2 and 65534).
„ RTP Port Range: 6 (This value must be an even number, and larger than or equal to
2); for IP SIP Phone, it should be at least 4 to support two concurrent calls.
Such RTP setting effectively designates 6 consecutive UDP ports ranging from 45700 to
45705 (inclusive) for media transaction.
Note: RTP/RTCP ports are used for media transmission. Those ports must be
consecutive and start with an even number. Besides, the total allocated UDP ports
SHOULD at least double the max concurrent calls supported by your terminal since
each active call takes 2 ports for RTP/RTCP.