If both parties (GW and SIP client) are not behind NAT (public IP, no firewall), you do not need nathelper+rtpproxy. Even in the case of a client behind NAT and the GW with public IP you do not need rtpproxy if the GW supports symmetric RTP (like Cisco GW does).

regards, klaus

support wrote:

Hi,

I have tested ser with a T1 trunk GW not behind NAT, but using fixed IP. I then disable the use of rtpproxy and nathelper. However, when I use PSTN call to a SIP UA, only ringtones could be heard but no voice passing through it.

Does it mean that rtpproxy + nathelper must be used even in the case when UA and PSTN GW are not behind NAT/Firewall?

Thomas

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