FInding the ESN of v60i

I just bought a v60i phone on ebay. I use a prepaid cell phone service
(Call Plus) which is compatible with the v60i. But I need to give the
prepaid service my ESN to activate my phone.

I can't find the ESN on the phone. There are a bunch of numbers under
the battery, but none of them are labeled "ESN". (Is it the same as
DEC?) Which number should I use?

Karen