Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Geraldine Callahan, NP
Nurse Practitioner in Nashua, NH · enumerated 2015.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1669865473
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Registry record
Entity type Individual (Type 1)
Name Geraldine Callahan
Credential NP
Sex Female
Practice address 39 Simon St Ste 5, Nashua, NH, 03060
Phone (603) 889-8648
Enumeration date Mar 18, 2015
Last updated in NPPES May 15, 2026
Taxonomy & licenses
363LP0808X Psychiatric/Mental Health Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 204352 (MA) Secondary
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 065522-23 (NH) Secondary
363L00000X Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 204352 (MA) Primary
363LP0808X Psychiatric/Mental Health Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 065522-23 (NH) Secondary
NP · Nurse Practitioner: An advanced practice registered nurse with graduate training, licensed to diagnose and treat, often with prescriptive authority.
About the NP 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.
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 Geraldine Callahan?
Geraldine Callahan is registered in NPPES with the primary taxonomy of Nurse Practitioner. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.
Other providers at this practice address
Browse all → Christine Isabelle Psychiatric/Mental Health Nurse Practitioner · Nashua, NH NPI 1992778427 Jeanne Courtright Clinical Psychologist · Nashua, NH NPI 1982777934 Dominique Beaulieu Psychologist · Nashua, NH NPI 1316215189 Derek Lavoie Psychologist · Nashua, NH NPI 1942075155 Erica Cote Mental Health Counselor · Nashua, NH NPI 1568284834
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2026-05-15.