When I press the Meet Me Softkey and enter the meet me number configuration I get a busy signal. It has been a while since this was tested and activated. What would cause the busy signal, is there something more that needs to be configured?
Checking the regions is good advice but I would also check the dialplan if I were you. I have found that many people break Meet-Me lines by adding a directory number that conflicts with the MML range. The CUCM does not (or at least did not) validate whether you were overlapping with the MML range or not. As an example, assume that your DID range is 5XXX (that is 5000 to 5999) and from this block, you allocated 510X for Meet Me Lines (that is 5100 to 5109). If somebody accidently created a phone with Directory Number 5100 and this Directory Number was visible from the same CSS as the MML patterns, your MML would essentially kick back a busy.
Of course, I did read in your thread that you tried to dial the intended MML from the PSTN which would suggest maybe an overlap like the one I describe may not exist. Though it still could be a problem if the phone who is initiating the CSS has a different set of partitions (and patterns) than the PSTN or if the overlapping pattern is configured on something that isn't registered or able to handle the direct call. Meaning, just testing from the PSTN is not in and of itself definitive proof.
So, to check the dial plan, do two things. First, go to Call Routing>Route Plan Report and search for the MML (use the exact pattern) that you are trying to open. See if that pattern exists anywhere in your dial plan. If you find an overlap, remove it and test. If you don't, then use DNA to analyze a call to the MML number from your test phone. In CUCM 6x/7x DNA is available from the Serviceability pages under Tools>Dialed Number Analyzer. From this tool you can analyze a call from a specific IP phone and IP phone line. Just search for your phone and select the line. Then enter the Directory Number of the MML (exact digits) and then look at the analysis. See if there is an overlap with another digit pattern that uses masks.
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