I would like to be able to archive my voicemail from my T-mobile cell
phone to my computer. I would like to find either:

a) A service that will dial up my voicemail periodically, record the
messages to mp3 files and email them to me.

b) A software package that makes in mind-numbingly simple to do this
myself. I know it's not rocket science to record a call with a
computer. But neatly parsing the messages into individual mp3s files?
This would be more time consuming.

PS. I realize there are services like maxemail and j2 that store
voicemail as sound files but this doesn't work for me as I get calls
on my cellphone. These are the messages I need to retrieve.

I would like to suggest that you consider:

c) Instead of using T-mobile voicemail, use a different one that does
have the vmail to email capability.  You can continue to use T-Mobile
, just choose to NOT use the free voicemail that comes with it.

I have Verizon, and really dislike their voicemail.  So, instead I use
another voicemail that also works for my business line.  Customers
leave messages all in one place, instead of multiple voicemail places.

I'm not sure I understand how you have this setup. When someone call
your cell phone do you forward it to your other voicemail number
somehow or do you just refer your callers to the other number?