A digital telephone answering device having speakerphone capability allows a recorded message to be played back and heard by the far-end party as well as over the local speakerphone by the near-end party during speakerphone operation as if it were a normal receive signal. The customer-specific variants provide for corporate personalization of data storage, retrieval, and input and output operationspresentations as well as workflows that use such data. In some embodiments, the pulse utilized for the reading may have an absolute value of voltage that is greater than or equal to the voltage utilized for the write operation. The thermal generator is transported in a metal housing. Optionally, the process may be repeated periodically to compensate for clock rate drift. These areas can be compared to obtain a reliable impedance value for the tissue.