Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum
Dr. John Michael Callahan, M.D.
Pediatrics Physician in Dubuque, IA · enumerated 2014.
Data current as of Jul 13, 2026 · sourced from CMS NPPES
National Provider Identifier
1851704480
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Registry record
Entity type Individual (Type 1)
Name Dr. John Michael Callahan
Credential M.D.
Sex Male
Practice address 1000 Langworthy St, Dubuque, IA, 52001
Phone (563) 584-3440
Fax (563) 584-3009
Enumeration date Jun 11, 2014
Last updated in NPPES Jul 5, 2017
Taxonomy & licenses
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.
Frequently asked questions
What is the NPI number for John Callahan?
The National Provider Identifier (NPI) for John Callahan is 1851704480, a Type 1 (individual) record in the CMS NPPES registry.
Where does John Callahan practice?
The practice location on file with NPPES is in Dubuque, IA. Providers can have multiple locations; NPPES lists the primary practice address.
Other providers at this practice address
Browse all → Marc Dicklin Physician Assistant · Dubuque, IA NPI 1205837408 Rebecca Watts Family Medicine Physician · Dubuque, IA NPI 1245217223 Ryan Stille Family Medicine Physician · Dubuque, IA NPI 1083694681 Martin Bagby Family Medicine Physician · Dubuque, IA NPI 1942269402 Karen Scott Neonatal-Perinatal Medicine Physician · Dubuque, IA NPI 1447210562 Kevin Mullen Pediatrics Physician · Dubuque, IA NPI 1710942701 Paula Aston Neurology Physician · Dubuque, IA NPI 1144286675 Katy Wethal Family Nurse Practitioner · Dubuque, IA NPI 1699732529
Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2017-07-05.