First you need to plug GPS antenna on RUT955 device appropriate connector. See it on back view of device: https://wiki.teltonika-networks.com/view/RUT955_First_Start#Back_view
Then enable GPS: Services -> GPS -> General configuration.
And check does your device updates location info: Services -> GPS -> Map. Wait few minutes for device to find satellites first time. If Fix coordinates are not updated, change GPS antenna location.
If your device updates fix coordinates you can enable GPS data sending to server via NMEA, HTTP, AVL protocol. RUT955 GPS settings are explained on Teltonika wiki: https://wiki.teltonika-networks.com/view/RUT955_GPS
Protocol depends on third party application server. Here are some examples of third-party platforms for RUT955 are:
Also you can use Teltonika RMS, it allows you see device location on device map no need to configure GPS data server.
I have asked a company trading in this field. here they are : dinh vi cho xe may
They said they need a SIM card