Browse to the user account in the admin GUI, and under the general tab, click show by DID numbers, new, add DID and apply. You can also add the DID in the CLI with con t, voice user xxx, and then DID nxxnxxxxxx.
Here is an example of adding did 21612345678 to existing user 214. Don't forget to write memory when all done. If the DID is not in the system, the call is not routeable, and you will get a reorder tone or intercept message from the carrier.
NV7100(config)#voice use 214
Configuring Existing User "214".
Also make sure your SIP voice trunked-group has the DID added as an accept XXX-XXX-XXXX cost 0 so the trunk will accept call. I think that is the step you are referring to that might be missing.
Thanks all. That is great info. Come to find out, I had made all the proper settings but had forgotten to save them out...
Sorry for the trouble.