A relatively placid market may have slowed T-Mobile’s roll in the third quarter, according to Deutsche Bank analysts. But the upcoming release of Apple’s iPhone X could roil competition heading into the holiday season.

Carrier promotions for the new iPhone 8 and 8 Plus have been notably less aggressive this year than last year, signaling something of a détente among the nation’s largest wireless network operators. Sprint appeared to up the stakes two weeks ago when it sweetened its iPhone 8 campaign, offering a free 18-month lease to users who activate a new line of service and trade in a current high-end handset, in a sign that its preorders of Apple’s new phone may not have met expectations.

Sprint’s rivals have declined to follow suit, though—thus far, at least—in an indication the market is less competitive than some had expected. The trend has pleased investors concerned about the high cost of heavily discounted handsets, but it could prove challenging for T-Mobile, which has consistently gained market share over the last few years.

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“While T-Mobile continues to take lead share of industry net adds, a somewhat slower-than-expected iPhone 8 upgrade cycle could weigh on near-term gross/net phone adds,” Matthew Niknam of Deutsche Bank wrote in a note to investors this morning. “We have recently referenced a more benign promotional environment in September (vs. last year’s ‘free iPhone 7’ promos) as a tailwind for industry margins, but as a catalyst for less industry switching activity.”

That could change with the release of the iPhone X, though, which is expected to go on sale Oct. 27 and start shipping a week later. The handset will sport a starting price tag of $999 and will include high-end features such as wireless charging, an OLED screen, facial recognition and an edge-to-edge screen.

The phone will face significant competition at the high end of the market from devices such as Samsung’s Galaxy Note 8 and Google’s second-generation Pixel. If carriers opt to back the iPhone X in a big way, though, more consumers will be enticed to switch service providers late in the fourth quarter. And that could help T-Mobile regain some momentum as the carrier continues to expand its retail presence and tap an enterprise market in which it has failed to gain much traction.

“(W)e believe 3Q may not show the same type of seasonal lift in volumes for industry disruptors (as we may have been expecting); it could be the case that T-Mobile (and others) see a deferral of heavier volumes/switching activity into 4Q once the iPhone X is launched in late October,” Niknam wrote. “Early share gains in commercial remain a consistent tailwind, while we expect greater contribution from expanded network/retail footprint in 2018.”