This has been asked plenty of times before, please try searching for answers in CSC before posting.
The answer is no, CUCM doesn't provide any kind of authentication.
If meet-me is started, if you can dial it, you'll join.
A workaround on which you can find plenty of references on previous posts is to use Unity or CUC to handle the call transfer and you'll be prompted to accept the call or send it to VM before joining.
If you're looking for a numeric code then you'll need to either do something with UCCX/UCCE or look into MeetingPlace.
HTH
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www.cisco.com/go/pdihelpdesk
HTH
java
if this helps, please rate