(Pocket-lint) - O2 has joined EE and Vodafone in offering the cellular version of the Apple Watch Series 4.

New and existing iPhone pay monthly users can now purchase the smartwatch through O2 on a number of price plans, and use it to make calls and stay connected, even when not in range of their handset.

When Apple first launched an LTE version of its Watch (with Series 3) it exclusively partnered with EE. Vodafone connectivity was added at the end of last year. Now O2 supports the device.

Three is the only one of the big UK networks yet to announce its intentions to carry Apple Watch - likely because it is still working on eSIM technology support.

O2 supports both Apple Watch Series 4 and Series 3 Cellular editions. And, if you purchase either between now and Wednesday 18 December 2019, you will get six months of free airtime for your watch.

That means an Apple Watch Series 4 on O2 costs £14.50 per month for 36 months for the device plan, while airtime will be free for the first six months. That will then rise to £5 per month.

You also have to pay £20 upfront.

An Apple Watch Series 3 costs £9.99 per month for 36 months for the device plan. Again, you get airtime free for the first six months, which then rises to £5 per month.

It also requires a £20 upfront fee.

Other plans can be found at o2.co.uk/apple-watch.

Writing by Rik Henderson.