Since you only use the Nonoh account for outgoing, maybe what you want to do is setup Nonoh on Voice Gateway 3 (IF it doesn't require registration with their Sever to place outgoing calls) and setup another SIP account on SP2. Then forward your calls to your OBi device via SIP URI to that provider, which will handle the NAT issues. In my case, I have a free UK DID from UKDDI and forward all incoming calls to my
VOIP.ms account (which is configure on SP2) via SIP URI. Maybe a free Callcentric IP Freedom account will serve this purpose if Nonoh doesn't accept inbound SIP URI calls.
Also, you could try to setup your OBi/Router for direct inbound SIP URI calls by following this generalize setup for the Linksys device (Note: There are some Linksys features that is note readily apparent on the OBi device, so maybe OBiSupport could provide some help in this regard):
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Here's a more general set of steps to properly set up a
PAP2/SPAxxxx type ATA behind a NAT router, that should work under just about any conditions.
Browse to the ATA's advanced, admin level web configuration. Under the SIP tab:
1) Record the port number specified by RTP Port Min.
2) Record the port number specified by RTP Port Max.
3) Set Handle VIA received to yes.
4) Set Handle VIA rport to yes.
5) Set Insert VIA received to yes.
6) Set Insert VIA rport to yes.
7) Set Substitute VIA Addr to yes.
8 ) Set Resp to Src Port to yes.
9) Set STUN Enable to yes.
10) Set STUN Server to your choice for STUN server, eg "stun.voxalot.com".11) Set Ext RTP Port Min to match the value recorded in step 1). May be omitted depending on router's NAT implementation.
Under the Line 1/2 tab:
12) Set NAT Mapping Enable to yes.
13) Optionally, set NAT Keep Alive Enable to yes. Isn't really necessary with ports forwarded.
14) Make a note of the value of field SIP Port.
15) Set Ext SIP Port to the value from step 14). May be omitted depending on router's NAT implementation.
16) Set Ans Call Without Reg to yes.
In your router's setup:
17) Forward the port number from step 14) for UDP, from your router to the ATA.
18) Forward the range of port numbers defined by the values from steps 1) and 2) for UDP, from your router to the ATA.
Finally, in your
"international DID provider's" setup, make sure that the SIP forwarding goes to the same port number as recorded in step 14).