Millions of people who pre-pay their wireless bill every month won’t be able to add the new Apple Watch to their service.
All four major wireless carriers—Verizon, AT&T, Sprint, and T-Mobile—confirmed to Fortune on Wednesday that only customers on regular monthly plans will be able to sign up for Apple Watch Series 3 cellular service for an LTE plan.
Apple unveiled its Apple Watch Series 3 on Tuesday alongside three new iPhone models and a revamped Apple TV set-top box. The new iPhones, the 8 models and iPhone X, will work fine for customers on prepaid service, which typically costs less and doesn’t require a credit check. But the new Apple watch, which has LTE cellular connectivity for the first time since the original Apple watch debuted two years ago, will only be accepted on monthly, or postpaid plans for an extra $10 monthly at Verizon, AT&T, Sprint, and T-Mobile.
Prepaid plans are most popular in low-income areas, but are also commonly used by students and people who just want to save money on their wireless bill.
Get Data Sheet, Fortune’s technology newsletter.
The Apple Watch may have been considered a luxury item initially, but Apple has steadily cut the price of entry. After Tuesday’s announcement, Apple lowered the price of its original watch to $249. The new Series 3 version with a cellular connection starts at $399.
Although not a breakout hit, Apple Watch has steadily increased sales with a focus on fitness tracking, notifications and an array of fashionable bands. Apple has not disclosed any sales figures for the Watch.
The big carriers have been increasingly competing for prepaid customers, but generally without using their main brands. AT&T offers prepaid service under its Cricket Wireless brand. Sprint owns two prepaid brands, Boost and Virgin. T-Mobile mainly relies on MetroPCS to offer prepaid service, while Verizon, which has not emphasized the segment much, uses its one brand for all kinds of plans.
At the end of the second quarter, T-Mobile (tmus) had 20 million prepaid customers, AT&T (t) 14 million, Sprint (s) almost 9 million and Verizon (vz) 5 million. All of the carriers have more subscribers for postpaid service.