FreePBX in cloud with local handsets

Hi everyone Im hoping someone can assist here as Ive been bashing at this for 3 days and its done my head in.

Im running asterisk FreePBX in amazon cloud.
My local network has a simple adsl connection with static IP. Basic modem/router into a cisco catalyst 2950 switch.
The handset is a yealink t38g.

I am able to register the handset to the server and make calls but unable to call extension to extension or recieve calls to the handset.

So Ive tried using the built in sip adapter on the modem/router.
Success - I can recieve calls to that extension.
Ive also tried the soft phone built into my HOX (HTC One XL) and I can recieve calls to that extension.
Great Im guessing it has something to do with NAT
So sip show peers shows any extension behind NAT as unreachable.

I discovered this thread which was the closest to my problem and hes talking about router firmware versions causing the problem.

So Ive tried 4 different routers.
billion bipac 7401vgp r3 (this is the one where the inbuilt sip worked)
billion bipac 7300
tplink td w8901G
dynalink rta 1046vw

Any suggestions?

Dump trying to use Amazon for your PBX.

I dont think its amazon related but in any case what do you suggest?

I found the issue.
In asterisk sip settings set NAT “route” enter the public IP of your box, and in local networks enter the ip subnet of any network your traversing into.

Also a note on performance.
Performance with an ec2 micro instance has been flawless. Ive tested up to 5 simultaneous calls and the instance delivered without fail. (It may be able to do more but thats all the handsets I had) I believe this setup is suitable for any soho, micro business and even small business. I dont know big a business would have to be to need more than 5 simultaneus calls.

A word of obvious caution. harden the hell out of it lest you become another hack statistic. Securing should be quite effective using,
static ip addresses at each end point,
Conservative use of amazons firewall rules,
following general freepbx hardening instructions.

Best of luck everyone thanks for the assistance, great communitiy.


Steve you probably won’t get too much response from the FreePBX forum on the suitability of Amazon, as most of us have looked at it and quickly decided it was not really suited for hosting a PBX. A while back the folks over at PBX in a Flash were playing with and testing Amazon extensively, the conclusion was summarized in this quote:

"Amazon Micro instance has burst capacity which gives it the capability to support lots of extensions and numerous calls for short periods of time. Once you start actually using a system heavily, you’ll need a much beefier flavor of EC2 which gets expensive fast because the regular instances don’t have burst capability. A dual-core Atom machine or a quad-core PC then becomes a much better option in terms of operating cost.

To put it less charitably, micro instances give the appearance of limitless capacity which quickly evaporates once you begin to actually need it. " (See the full thread here:

Thats correct, the issue wasn’t with amazon at all - it was the configuration of freepbx. I, like yourself also suspect a micro instance wouldnt be suitable for the enterprise enviornment thank you for confirming.


Yes, for future people that find this thread these settings are outlined in the wiki, detailed info here

There are guides on most of the modules.