Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. William J Sonstein, M.D.

Specialist in Rockville Centre, NY · enumerated 2006.

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

National Provider Identifier

1669495305

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Registry record

Entity type Individual (Type 1)

Name Dr. William J Sonstein

Credential M.D.

Sex Male

Practice address 100 Merrick Rd, Suite 128 W, Rockville Centre, NY, 11570

Phone (516) 255-9031

Fax (516) 255-6230

Enumeration date Jul 25, 2006

Last updated in NPPES Jul 8, 2007

Taxonomy & licenses

174400000X Specialist Other Service Providers · License 195202-2 (NY) Primary

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

Other identifiers

Identifier	Type	State	Issuer
01827870	Medicaid	NY	-

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.

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Frequently asked questions

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is William Sonstein?

William Sonstein is registered in NPPES with the primary taxonomy of Specialist. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2007-07-08.