The Pitney Bowes website states that P700 is the model number of the DM100i postage meter, which features the ability to refill postage by phone. In order to successfully refill your meter by phone, you need to have a funded account with Pitney Bowes.
To use the refill-by-phone feature, you need to connect your meter to a phone line, and then press the "Add Postage" button on the meter. Your Pitney Bowes account can either be prepaid using an e-check or funded via the "Purchase Power" program, which automatically adds funds as needed and bills you at a later time. E-checks take five to seven days to process.