I have a Merlin Legend R7. I just put a used MLM 700 2 port in the system. All of the lights seem to be the appropriate green, but I have no idea how to access or login to the voicemail. I have found information on how to program etc. However, I can't even figure out how to talk with the unit. Any help would be much appreciated.

I would start with downloading a manual from Avaya's web site. Have a try at it following the installation section and post again if you need help. Otherwise I would recommend an experianced installer onsite to assist you.