WILLIAM CHARLES O'CALLAHAN JR. MD
NPI 1114964186
Emergency Medicine in Holden, MA
About William Charles O'callahan Jr. Md NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
WILLIAM CHARLES O'CALLAHAN JR. MD (NPI 1114964186) is an individual emergency medicine provider in Holden, Massachusetts, licensed in Massachusetts (79001) and active in the NPI registry since May 2006. He is enrolled in Medicare PECOS, is affiliated with Umass Memorial Medical Center/university Campus, and maintains 3 additional practice locations.
NPPES Registry Identity
Specialties & Licenses
Secondary Practice Locations 3
Medicare Participation & PECOS CMS
Medicare enrollment, assignment, and ordering and referring status from the CMS PECOS system.
Medicare Enrollment Status
Enrolled in Medicare and accepts Medicare assignment
William Charles O'callahan Jr. Md is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.
Areas of Expertise CMS Part B claims 14
Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Umass Memorial Medical Center/University Campus
Acute Care Hospitals · Worcester, MAPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 01520 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
Other Providers at the Same Location NPPES 9
Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.
Frequently Asked Questions NPPES & CMS
Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.
What is William O'callahan's NPI number?
The NPI number for William O'callahan is 1114964186. It was assigned to this individual provider in the NPPES registry on May 31, 2006.
Where is William O'callahan located?
William O'callahan practices at 5 Shrewsbury St Ste D, Holden, MA 01520. The listed phone number is (508) 829-3800.
What is William O'callahan's specialty?
The primary specialty registered for this NPI is Emergency Medicine with taxonomy code 207P00000X.
Is William O'callahan enrolled in Medicare?
Yes. William O'callahan is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.
Is William O'callahan affiliated with any hospitals?
According to CMS data, William O'callahan is affiliated with Umass Memorial Medical Center/University Campus.
When was this NPI record last updated?
The NPPES record for William O'callahan was last updated on January 21, 2025. NPI Profile syncs with the weekly NPPES data releases published by CMS.