If you are having problems with remote users connecting to your OCS Edge server, check out this OCS Remote Connectivity Analyzer put out by Microsoft: https://www.testocsconnectivity.com/.

When you finish the test, you should get this screen:

You can then dig down into each step of the test to see the details.

If you have any errors, it will give you links to the OCS 2007 R2 Troubleshooting section of TechNet:
http://technet.microsoft.com/en-us/library/dd572865(office.13).aspx

External access is the most confusing and complex part of deploying OCS.

Hope this helps!