Search the Medicare Claims Processing Manual, Chapter 12, for the word "telephone" and the sentences are filled with negatives.  Here's the section from the Manual labeled telephone calls:

B.  Telephone Calls
 
Telephone calls (codes 99371-99373) may not be paid separately.  Payment for telephone
calls is included in payment for billable services (e.g., visit, surgery, diagnostic procedure
results).

99371-99373 are deleted codes, replaced with codes 99441--99443.  Those time-based codes have very specific descriptions which state that the telephone call may not have taken place relating to an E/M service provided in the past 7 days or in the next 24 hours.  Medicare assigns these codes a non-covered status. 

If using these codes for your non-Medicare patients, check with your third party payers to see if they are considered: covered, non-covered, or bundled.  If non-covered or bundled, ask your representative if you are permitted to bill the patient for the service wtih a waiver of liability in place.  Read the full CPT® definition in the CPT® book.

There are instances when phone calls are payable as part of care plan oversight (CPO).  There are two sets of codes to review: Medicare CPO and non-Medicare CPO.  Both require that the patient being cared for is complex, and the covered phone calls are not to the patient.

Physicians and NPPs spend enormous amounts of time performing services which are not currently reimbursed separately from the pre-post work of other services perfomed.