If you want to leave your iPhone at home without missing out on iMessages, calls, and other notifications, now you can — if you have the right Apple Watch. Specific Apple Watch models are able to connect via 4G LTE, enabling you to go on a run or an errand without needing to carry your phone.

So far, three models of the Apple Watch support this feature:

These models tend to cost more than the base models that only support Wi-Fi and GPS connectivity (up to $100 more, depending on the smartwatch model you’re looking for). Additionally, you’ll have to pay a monthly fee to your carrier in order to use the LTE connectivity.

Activate your Apple Watch on an LTE network

The first step is to open up the Watch app on your iPhone; it’s where you manage everything that has to do with your smartwatch. Scroll down and tap on “Cellular” and then tap on “Set up Cellular.”

What you see next — and how much you pay — will vary depending on your carrier. Since I’m a Verizon customer, it asked me to sign in with my phone number, then verify that I want to add the Apple Watch to my plan.

The carrier you use can depend on the model of your Watch. (Here’s Apple’s list of supported carriers.) According to Apple, your phone and Apple Watch must be on the same carrier. However, the Apple Watch supports up to five cellular plans, so you can switch carriers with a reasonable amount of confidence.

Here’s what it could cost with some of the major carriers:

If you have a connected device data plan (a flat fee for a set amount of data per month) with Verizon, adding an Apple Watch costs $5 per month as well as a $30 activation fee when you add it to your plan. You can activate the Apple Watch on a single device plan that offers 1GB of data for $10 per month. If you have an unlimited phone plan, it costs $10 more per month.

T-Mobile charges $10 per month to add an Apple Watch to your plan, and the carrier may charge you a $20 fee for activation. This price seems to be consistent no matter which plan you have at T-Mobile.

AT&T charges $10 per month to add an Apple Watch to your plan whether you have an unlimited plan or are just going to connect a single device. It may charge you up to $45 to activate the Watch.

Sprint doesn’t offer standalone plans for the Apple Watch, so you’ll have to be enrolled in a data plan for your phone. It costs $10 per month to add a cellular-enabled Apple Watch to your Sprint plan.

Once you’ve successfully added the Apple Watch to your mobile plan, you can switch the cellular function on or off by swiping upward on the home screen of the Apple Watch, then tapping the top left option that looks like a radio tower. It will turn green when cellular is activated, indicating that you’re now free to leave your phone at home without worrying about missing out on a notification.