ZyXEL Communications MAX208M2W SERIES, User Manual

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Chapter 10 The VoIP Account Screens
MAX208M2W Series User ’ s Guide
142
3 The MAX208M2W Series uses the public IP address and port number in the SIP
packets that it sends to the SIP server (
C ).
Figure 65 STUN
Outbound Proxy
Your VoIP service provider may host a SIP outbound proxy server to handle all of
the MAX208M2W Series
’ s VoIP traffic. This allows the MAX208M2W Series to work
with any type of NAT router and eliminates the need for STUN or a SIP ALG. Turn
off a SIP ALG on a NAT router in front of the MAX208M2W Series to keep it from
retranslating the IP address (since this is already handled by the outbound proxy
server).
NAT and SIP
The MAX208M2W Series must register its public IP address with a SIP register
server. If there is a NAT router between the MAX208M2W Series and the SIP
register server, the MAX208M2W Series probably has a private IP address. The
MAX208M2W Series lists its IP address in the SIP message that it sends to the SIP
register server. NAT does not translate this IP address in the SIP message. The SIP
register server gets the MAX208M2W Series
’ s IP address from inside the SIP
message and maps it to your SIP identity. If the MAX208M2W Series has a private
IP address listed in the SIP message, the SIP server cannot map it to your SIP
identity.
Use a SIP ALG (Application Layer Gateway), STUN, or outbound proxy to allow the
MAX208M2W Series to list its public IP address in the SIP messages.
Speed Dial and Peer-to-Peer Calling
Speed dial provides shortcuts for dialing frequently used phone numbers. You can
map a phone number to an alphanumeric keypad key (
1 to 9 ) and then use that
keypad key to call the phone number (press and hold the key for one second or
longer). Use this screen to add, edit, or remove speed-dial numbers for outgoing
calls.
You also have to create speed-dial entries if you want to make peer-to-peer calls
or call SIP numbers that use letters.
A
1
2
3
NAT