Chapter 10 The VoIP Account Screens

3The WiMAX Device uses the public IP address and port number in the SIP packets that it sends to the SIP server (C).

Figure 91 STUN

NAT

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2

 

A

 

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Outbound Proxy

Your VoIP service provider may host a SIP outbound proxy server to handle all of the WiMAX Device’s VoIP traffic. This allows the WiMAX Device 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 WiMAX Device to keep it from retranslating the IP address (since this is already handled by the outbound proxy server).

NAT and SIP

The WiMAX Device must register its public IP address with a SIP register server. If there is a NAT router between the WiMAX Device and the SIP register server, the WiMAX Device probably has a private IP address. The WiMAX Device 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 WiMAX Device’s IP address from inside the SIP message and maps it to your SIP identity. If the WiMAX Device 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 WiMAX Device to list its public IP address in the SIP messages.

DTMF

Dual-Tone Multi-Frequency (DTMF) telephone call signaling uses pairs of frequencies (one lower frequency and one higher frequency) to set up calls. It is also known as Touch Tone. Each of the keys on a DTMF telephone corresponds to a different pair of frequencies.

Supplementary Phone Services Overview

Supplementary services such as call hold, call waiting, call transfer, etc. are generally available from your VoIP service provider. The WiMAX Device supports the following services:

•Call Waiting

•Call Forwarding

•Caller ID

Note: To take full advantage of the supplementary phone services available though the WiMAX Device's phone port, you may need to subscribe to the services from your VoIP service provider.

 

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WiMAX Device Configuration User’s Guide