In this case, there is no absolute answer. Depending on your needs and your supposed use of the GPS tracker, you will need, or not, a phone subscription. 

If you need real-time tracking...

In this case, a telephone subscription is imperative to get optimal results. If you want to follow in the footsteps of your cat, especially a vagrancy, or a parent with Alzheimer's who is at risk of getting lost, a  real-time tracking is necessary. But what role does the telephone subscription play here? In fact, a telephone subscription is a corollary to theusing a SIM card. In one GPS tracker, the latter acts as a transmitter: it will transmit via SMS the geo-location data of the vehicle, the pet or the person. This transmission can be programmed according to your needs. Transmission can even be done via the Internet. But for it to be done, the chip must be subscribed to a subscription with the operator. Hence the need for a telephone subscription.

If you don't need real-time tracking...

A phone subscription is not always necessary, if you use the GPS tracker rarely and sms consumption is low, you can opt for a prepaid sim card. 

We advise our customers to opt for sim cards with a plan because GPS trackers consume internet data.