Prefix 414-439 — Milwaukee Zone 1, WI

NANPA CO code assignment, current as of July 28, 2026.

Area code
414
Prefix (NXX)
439
Rate center
Milwaukee Zone 1
State
Wisconsin
Time zone
Central
Code holder
T-MOBILE USA, INC.
OCN
6529
Pooled
Yes (thousands-block pooling)
Assigned
2014-03-17
LATA
356

The 414-439 prefix belongs to area code 414 and is anchored to the Milwaukee Zone 1 rate center (WI). In NANP terms, the prefix — or NXX — determines the rate center a number is billed against.

Milwaukee Zone 1 is part of the Milwaukee-Waukesha, WI Metropolitan Statistical Area. For routing purposes it sits in LATA 356. Numbers here keep Central time.

The assigned code holder is T-MOBILE USA, INC., operating company number 6529, assigned March 17, 2014. This is a pooled prefix — expect numbers within it to be split across more than one carrier in 1,000-number blocks.

Caller ID showing 414-439 is not proof the call came from Milwaukee Zone 1: spoofing and porting both detach numbers from their origin. To verify a caller, hang up and dial the organization's published number, and report suspicious calls to the FTC.

Neighboring prefixes

Prefixes adjacent to 414-439
PrefixRate centerCode holder
414-436 Milwaukee Zone 1 ONVOY, LLC - WI
414-437 Milwaukee Zone 5 EON TELECOM, INC.
414-438 Milwaukee Zone 1 WISCONSIN BELL INC
414-440 Milwaukee Zone 1 AMERICAN MESSAGING SERVICES, LLC
414-441 Milwaukee Zone 3 ONVOY, LLC - WI
414-442 Milwaukee Zone 1 WISCONSIN BELL INC

FAQ

Where is 414-439 located?

The prefix is assigned to the Milwaukee Zone 1 rate center in WI, area code 414. It is part of the Milwaukee-Waukesha, WI Metropolitan Statistical Area.

Which company owns 414-439 numbers?

T-MOBILE USA, INC. holds the code, but the prefix is pooled — individual thousands-blocks can be assigned to other carriers, and numbers may be ported to any provider.

Is a call from 414-439 safe to answer?

The prefix itself says nothing about the caller. Legitimate Milwaukee Zone 1 businesses and spoofed robocalls can both display it. Never share personal data with an unverified inbound caller.