As before, the offer will also cover customers who want a free Google Pixel phone, Samsung Galaxy S7, as well as other current models and phones from LG and Motorola. Unlike prior promotions from other carriers, Verizon’s offer also includes free versions of the more expensive, larger screen versions of the phones, such as the iPhone 7 Plus, which sell for up to $800.

Also along the lines of previous offers, the deal is partly a way to deter customers from switching carriers in the future. The free phones are still billed in 24 monthly installments, but with Verizon giving a full credit to cover each payment. If a customer leaves within two years, the credits end and the remaining balance on the phone comes due.

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The revived promotional offer comes as growth has nearly stalled in the U.S. wireless market and the carriers are increasingly fighting to convince subscribers to defect. Only T-Mobile (TMUS) and Sprint (S) have added regular monthly phone customers recently, while Verizon (VZ) and AT&T (T) saw net losses in that most lucrative subscriber category.

The free smartphone offers can aid in reducing customer churn, analyst have said. They prefer the free hardware deals to offers for lower-priced monthly mobile service, which some carriers have also offered.

Verizon had previously offered free iPhones around the Black Friday shopping period. And back when the iPhone 7 first came out, all four carriers offered a free with trade-in offers. T-Mobile and Sprint said the offers greatly increased early demand compared to sales of last year’s iPhone 6s. AT&T and Verizon said their deals only modestly affected demand.

Apple (AAPL) won’t reveal actual iPhone sales until January, when it reports results for the final quarter of the year. And even then, the company never discloses how many iPhones were sold just in the United States.