John Schaller, M.D., M.P.H.
John Schaller, M.D., M.P.H. is a Preventive Medicine/Occupational Environmental Medicine Physician in Phoenix, AZ, registered under NPI 1093830333. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 4645 E COTTON CENTER BLVD BLDG 1 # 200, Phoenix, AZ 85040. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| G66859 | CA | Preventive Medicine/Occupational… primary |
| 17949 | AZ | Internal Medicine Physician |
| G66859 | CA | Internal Medicine Physician |
| 17949 | AZ | Preventive Medicine/Occupational… |
Licences are recorded in 2 states: CA, AZ. Providers licensed in several states often practise near a state border or deliver telehealth across state lines.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
Licensed in 2 states
This provider holds licences in 2 states: Arizona and California. The practice address on file is in Phoenix, AZ, but a licence in another state usually means they see patients there too — either at a second location or by telehealth. If the address above is far from you, it is worth calling to ask whether they practise closer to where you live.
- Licence
- 17949
- Specialty
- Internal Medicine Physician
Licence numbers are self-reported to NPPES at registration. They do not confirm a licence is currently active, in good standing, or valid for the specialty shown — only the state board can tell you that, which is why we link to each one.
What Preventive Medicine/Occupational Environmental Medicine covers
A preventive medicine physician who specializes in preventive medicine/occupational-environmental medicine, which is focused on protecting the population from occupational and environmental conditions. NUCC Health Care Provider Taxonomy, code 2083P0500X
All registered taxonomy codes
This provider registers 4 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 2083P0500X | Preventive Medicine/Occupational Environmental Medicine Physician Preventive Medicine/Occupational Environmental Medicine | G66859 | CA | primary |
| 207R00000X | Internal Medicine Physician | 17949 | AZ | |
| 207R00000X | Internal Medicine Physician | G66859 | CA | |
| 2083P0500X | Preventive Medicine/Occupational Environmental Medicine Physician Preventive Medicine/Occupational Environmental Medicine | 17949 | AZ |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1093830333 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 19, 2007 |
| Last updated | Sep 11, 2025 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D., M.P.H. |
| Practice address |
4645 E COTTON CENTER BLVD BLDG 1 # 200 Phoenix, AZ 85040 (602) 659-1123 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 9 | 3 | 8 | 3 | 0 | 3 | 3 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 9 | 3 | 7 | 3 | 0 | 3 | 6 |
Sum = 57 · next multiple of 10 = 60 · check digit = 3 · actual last digit = 3
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.