Verizon grudgingly admitted for the first time on Thursday that its sales of the iPhone 7 are up from last year’s iPhone 6S line, attributing the increase to its free with trade-in promotion. Competitors T-Mobile and Sprint have announced huge increases in sales, while AT&T said the new model was exceeding expectations.

“I know some of our competitors have made a big, big announcement around the iPhone 7 and how great it is. Of course, it’s great—it’s free,” Verizon CFO Fran Shammo said while speaking at the Goldman Sachs gs Communacopia conference in New York. “We saw some increase in our volume from ’15 to today, but I kind of attribute that to zero—it’s free to the customer.”

Ultimately, however, Shammo said he expects sales will slow at Verizon vz and only match the level of sales of the iPhone 6S last year.

“The question is when those promos end…does that continue,” he remarked. “I don’t know the answer to that yet, and I still believe that volume will be similar to ’15.”

 

 

With previously low expectations on Wall Street for iPhone 7 sales, Apple’s stock price has gotten a nice bounce from the carriers’ disclosures. Analysts had not anticipated that the big four wireless carriers would all offer such aggressive promotions.

Shares of Apple aapl are up about 8% since last Monday, when T-Mobile tmus CEO John Legere reported—in a live Periscope video on Twitter twtr —that the promotions for a free iPhone 7 with trade-in of an older model were working. T-Mobile was seeing record demand for the iPhone 7—almost four times higher than in 2014 when the iPhone 6 was setting records.

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A day later, Sprint s CEO Marcelo Claure said his company was seeing almost four times higher demand for the iPhone 7 than for last year’s model. And the next day, AT&T t CFO John Stephens said iPhone 7 sales were up compared to last year’s model. “We have seen a real improvement, exceeding our expectations,” he said.