Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. Cliff O'Callahan, M.D., PH.D.

Pediatrics Physician in Middletown, CT · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1811977663

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Registry record

Entity type Individual (Type 1)

Name Dr. Cliff O'Callahan

Credential M.D., PH.D.

Sex Male

Practice address 90 S Main St, Middletown, CT, 06457

Phone (860) 344-6300

Fax (860) 344-9249

Enumeration date Jan 18, 2006

Last updated in NPPES Dec 1, 2020

Taxonomy & licenses

207Q00000X Family Medicine Physician Allopathic & Osteopathic Physicians · License 040077 (CT) Secondary

208000000X Pediatrics Physician Allopathic & Osteopathic Physicians · License 040077 (CT) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

Read the full guide → Validate an NPI →

Frequently asked questions

Where does Cliff O'Callahan practice?

The practice location on file with NPPES is in Middletown, CT. Providers can have multiple locations; NPPES lists the primary practice address.

What is the NPI number for Cliff O'Callahan?

The National Provider Identifier (NPI) for Cliff O'Callahan is 1811977663, a Type 1 (individual) record in the CMS NPPES registry.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2020-12-01.