No Ring

you have correct DID info in the inbound route? try setting the catchall option to check.

Sounds like the phones are not completely registered with the trixbox server.

I am not familiar with your particular phone, but with Polycom and Cisco, the screens indicate if they are registered with symbols (polycom has a phone outline that fills in the handset and body of the phone depending if it is fully registered, cisco puts an X by the phone symbol if it is not registered).

I have had phones that were not completely registered that would make calls but would not receive them.

Try putting nat=no on one of the phones in freePBX in extensions and then dial that phone.

Voice mail will answer even when there is no physical phone connected to the system. So you can have voice mail boxes with ext numbers without having a telephone on the system. We use this for IVR situations on our system...such as an ext for Vendors to call.

So this leans me toward your phones not being completely registered

In freePBX goto freePBX System Status and see how many IP phones are online under statistics.

Can you take them back? I tried a DLink 140 and it was horrible. I seem to recall it was a pain to get working properly and was really not a good phone. If you want something else that is low cost, try the Level One VOI-7000.
If you can't off-load these things, go to a asterisk command line and run SIP SHOW PEERS. This will show you what extension you have set up, and which ones are believed to be on-line, with their IP addresses. From the asterisk command line, and run SET VERBOSE 9. go pull the power out of a phone and and then reconnect it. Watch the console. You should get a extension registered with some details some time after the phone boots. if you have registered extensions and they show up when you boot them, go check the logs. You'll need to add the log file viewer in FreePBX to see those easily. Grab the last few lines that look relevant and post them here.
Go to the phone console and check all the settings about Proxy address, username, and password. Try putting the IP of the Trixbox in every place that looks remotely relevant. There may also be more than one username box. I still have one of these getting dusty at the office I can look at.
Check again if you can send them back.

I had the same problem before. Try to check the codec.

I would have never guessed fixing the Trunks's register string would fix the registration with the X-Lite phone. The original string was created by the wizard and I didn't realized I had to change the ending to my static IP. The original looked like this "xxxxxxxx@voipstreet.com" and I forgot to change out the voipstreet.com with my own IP. That fixed my registration issue!!! Yippeeee.....

On with the next issue:

When I attempt dial an external number using 91xxx-xxxx, it rings immediately (way too fast) on the X-Lite/7960 but never connects on the other side.

The trunk in/out is showing "unmonitored"

voipstreet_in/myusername xx.xx.xx.xx 5060 Unmonitored
voipstreet/myusername xx.xxx.xx.xx 5060 Unmonitored

Any ideas?