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Unread 10-01-2009, 05:57 PM   #14
boatman
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Quote:
Originally Posted by Juste View Post
So, the questions are still there. But since the other STUN does the job I will put them on hold until somebody more knowledgeable than I am gives me a clear answer.
Initially I was was puzzled that your ATA could not be contacted just because a STUN server failed. Then I thought maybe you don't have "Handle VIA received" and "Handle VIA rport" set yes. When STUN is not available there is another way the ATA can learn it's public IP address and public SIP port number. It uses "Handle VIA received" and "Handle VIA rport".

Apparently you have "Handle VIA received" and/or "Handle VIA rport" set no, so without STUN your ATA didn't know some important details, part of the SIP address at which Voxalot tries to contact your ATA to connect calls. Without the public IP address and public SIP port number your ATA registered using it's LAN IP address and LAN SIP port. Voxalot then tried to connect incoming calls to a wrong SIP address, for example; 123456@192.168.1.101:5060, note the LAN address and non-NATed SIP port number, which of course did not reach your ATA. After some time (Ring duration at your Voxalot account) Voxalot connected the call to your voice mail.

Below are some important settings for Linksys ATAs behind one or more NAT routers, when not using port forwarding in the router(s). If you may be behind symmetric NAT I recommend setting "Symmetric NAT Handling" to 'Yes' in your Voxalot account.

(under SIP tab)
Handle_VIA_received: yes
Handle_VIA_rport: yes
Insert_VIA_received: yes
Insert_VIA_rport: yes
Substitute_VIA_Addr: yes
Send_Resp_To_Src_Port: yes
STUN_Enable: yes
STUN_Test_Enable: no (or yes to automatically detect if you are behind symmetric NAT)
STUN_Server: stun.voxalot.com:3478 (or any STUN server such as 'stun01.sipphone.com:3478' or 'stun.sipgate.net:10000')
NAT_Keep_Alive_Intvl: 179 (sometimes 119 or 59, use highest number that works)

(under Line_1 and Line_2 (or PSTN_Line) tabs)
NAT_Mapping_Enable: yes
NAT_Keep_Alive_Enable: yes
NAT_Keep_Alive_Msg: 0000
NAT_Keep_Alive_Dest: $PROXY
Register Expires: 3600

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Optional settings, steps 1 - 4:
Sometimes its preferable to operate the ATA independently of a STUN server. The benefit is that phone service can continue no matter if the STUN server is working. See steps 1 to 4 below.

1. Forward the SIP ports and the RTP port range from the router to the ATA.
2. Set "STUN Enable:" no
3. Set "NAT Keep Alive Enable:" no
4. The ATA must learn it's public IP address, either through normal SIP registration, or place your public IP address in the 'EXT IP:' field).
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