The Apple Watch functionality has improved over time. An iPhone used to need to be left on and connected for Cellular to work on the Watch. I was under the impression that with advances in eSim and Software Updates the watch could now make and receive calls without any dependence on the iPhone, except perhaps for the occasional software update). Recently I learned that with AT&T that NumberSync is necessary and call do not ring on cellular unless the iPhone is left on and connected to the internet.

What is the current state of cellular connectivity on Apple Watch? According to Apple.com Cellular allows you to leave your phone behind and just use the Watch, but does the phone need to be online somewhere?

  • This is not about Apple Watch functionality. It’s about your cellular service provider technical ability and business willingness. Commented May 15, 2022 at 6:00
  • Yes, I have pondered that this may be an issue with AT&T, specifically still pushing the Number Sync feature.
    – user711393
    Commented May 15, 2022 at 11:22

2 Answers 2


I would have to test this specific case to answer 1/2 of it for certain and I will get back & edit this part of my answer; unfortunately it does seem like this is now the case (as a NumberSync user myself).

However, What should still independently work is if you were to call the ‘spare’ / ‘burner’ phone number which you may or may not recall that it has.

You can find this phone number in your AT&T account profile.

  • I just tried calling the burner number directly and it doesn’t ring and just goes to voicemail.
    – user711393
    Commented May 15, 2022 at 2:11

AT&T.com has the option to download a new eSim to the Apple Watch from the Account page. This also triggers the re-setup of Number Sync which seems to help.

I also spoke with Apple Support and they did say the iPhone may need to be on and in service for the Apple Watch to receive incoming calls.Use your Apple Watch without your iPhone nearbyIf you scroll down in this article to the second part, Phone calls and texts are not included in the things the Watch can do when the iPhone is off.

"If you can't connect to Wi-Fi, cellular, or your iPhone when your Apple Watch is disconnected—for example, if you're hiking in an area without Wi-Fi or cellular signal, or your iPhone is off—you can still do these things."

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