The Apple Watch won't become popular until it can function independently from iPhones, according to Piper Jaffray analyst Gene Munster who spoke at Business Insider's IGNITION 2015 conference on Wednesday.
Munster predicts that'll happen in 2017, at which point he expects the company will sell a staggering 40 million Apple Watches. To put that into perspective, Munster estimates the tech giant sold an estimated 11.8 million units in 2015.
From an untethered smartwatch, you could make or receive calls, send or receive texts, and potentially even stream music, all without needing your smartphone. It's especially alluring for times when carrying around a relatively bulky and heavy smartphone isn't ideal, like during a workout.
For a smartwatch to do those things without tethering to your smartphone, it would need a connection to your mobile carrier's data network, such as 3G, 4G, or LTE. And for that, it would most likely need it's own SIM card.
For now, only Samsung makes smartwatches that can work totally independently from a smartphone, including the Gear Live and Gear S2. Both only connect to AT&T's 3G networks with a special "e-SIM", which is fine for phone calls and text messages, but might be a little slow for music streaming.
The e-SIM could be linked to your primary phone number with AT&T's NumberSync technology, so you wouldn't need to get a separate number for your smartwatch.
LG almost came out with the Urbane 2 with LTE connectivity, but it was pulled at the last minute because of some technical difficulties that prevented the watch from working properly.
