Credit Balance on new Expense Account

[Tad Marko]

Howdy!

I've started this year getting all my finances into GnuCash, so I have
all of my accounts starting at 1/1/2007. Whatever balances they have
at that moment is the beginning balance I enter them with. This is
working fine for credit card and bank accounts, but I have a telephone
bill that I overpaid by quite a bit last year so on 1/1/2007, it has a
substantial negative balance. I would like to track the new bills at
they whittle down this balance, showing them paid against this balance
until it is depleted. What is the best way to reflect this?  I'm
thinking that I may have to turn this into an asset account, which I
really don't want to do for this unusual circumstance.

Thanks for any suggestions.

Tad