With portforwarding,

1. You need to enable for two ports. (one for signalling and one for
rtp(voice))
2. Settings in the UA must have options to set this two fields. (NATIP and
RTPPort)

Then you can make peer to peer calls.

Security risks:

If someones knows the port details, then they can disturb your
communication. sending unwanted packets to voice port, makes voice quality
poor.

To avoid all these,

If you have stun enabled phone, then just only one port forwarding is enough
for signalling, rtp ports are dynamically allocated and the natip & natport
will be taken from the stun.
STUN works fine depending upon the NAT Type between the user agents.

For fewer NAT Types, stun will not work. (Nat Type IV combination)


Kannaiyan

----- Original Message -----
From: "Murat Artun" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, January 04, 2007 10:24 PM
Subject: [Sip-implementors] Two SIP UAs both behind NAT


> Hello,
>
> What would be the possible call scenarios for two SIP UAs both behind NAT?
>
> Should a SIP proxy always be used?
>
> In case when A SIP proxy is not used, is it possible to make a direct
> call from one to other by using some workaorunds such as port
> forwarding on the NAT?
>
> --
> M u r at  A r t u n, MSc.
>   Software Engineer
> _______________________________________________
> Sip-implementors mailing list
> [email protected]
> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>


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