[sgt]

They claim several times that it does not require cell phone coverage, but from the screen shots on http://www.play-tag.com/info/#about it appears that you have to log into the app before you can use it?

[duiker101]

it probably means it doesn't use the cellular network, so it's doesn't require a SIM. To connect you can use wifi.

[play_tagapp]

Also the only feature that requires this is for the health info of the dog which is stored on the cloud - all other features do not require cell phone service.