I have years of experience with GSM GPS trackers.
I work at daily basis with GPS trackers and reception servers.
There are few things that affect the devices you would need.
So place let me know answers to these few questions.
First you should decide what kind of protocol you would like to have ?
Most basic GPS trackers support TCP and UDP, but there is also devices with support for RabbitMQ.
With TCP / UDP you will have to code your own reception server.
What is your use case of the devices ?
- What are you tracking ? Vehicle like car or do you want to track
- Do you have external power supply, or do you need large internal
There is also lot of different price options depending on the features of devices.
Amount of Digital & analog inputs / outputs, serial ports, CAN support, OBD2 support, external / internal antennas, 1-wire... etc.
But if you would like to have reliable actually GOOD devices, for vehicle tracking with great but basic features, that is graphically configurable and supports TCP / UDP with easy to understand protocol i would suggest to go with Teltonikas devices.
Here is few Teltonika models.
FMB010 is OBD2 powered devices with out support for OBD2 protocol ( only powered from OBD2 port of the car, very easy to install. ) with accelerometer and bluetooth support.
FMB920 is very basic level wired tracker with accelerometer and bluetooth support ( terminal, and temperature sensors for example. ).
Maybe you do not have external power supply for the devices and you want to track your self for example.
Teltonika TMT250 personal tracker
Small handheld devices with chargeable internal battery ( 800 mAh Li-Ion ).
There is also configurable alarm button.
All these Teltonika devices support GPS, GLONASS, GALILEO, BEIDOU.
For communication : GSM (2G) Quad-band 850 / 900 / 1800 / 1900 MHz.
If you live in USA there is specific devices to be used in side USA that support LTE for example. like FM36M1
Of course there is more simple devices in the market, but these devices are actually what u would use in real life scenarios, and they are good quality with great features.
For example FMB010 supports sending X,Y,X values of the accelerometer.
I have experience with many different usage scenarios, and devices manufacturer so tell me more about your use case so i can give you specific devices model from great manufacturer.
Sorry for my bad english, and P.S. I'am not connected with Teltonika or with any other GPS devices manufacturer, i just have years of experience using their products.