Before you can use the gps tracker Reachfar you need to authorize your cell phone number of your smartphone / cell phone.
Authorization means to allow just only that number to send instruction commands to the gps tracker and to disallow requesting a location by call or sms from other numbers. This is a kind of security feature.
Don't use the number in the tracker for authorization, use the number of your cell phone (!). This authorized number is also called admin number, master number or center number. Please use the international number format (41,43,49, etc.) without leading +.