[andyp]

Has someone used arduino with GSM shield to transmit and receive telemetry over mobile phone net? How do set up IP network telemetry in GCS? Is receiving and sending possible with the GCS?

Or should I use the model and set telemetry over main port and use two arduinos one on the UAV with GSM and one over ethernet shield at home?

[AerialPerPlexity]

Are you talking about  using the app librepilot2go

[TheOtherCliff]

Telemetry can work over a standard serial line.  If you set up a port on the FC to do telemetry, and connect a device that translates serial to GSM (and also do serial to GSM on GCS), that should work.

[Mateusz]

Has someone used arduino with GSM shield to transmit and receive telemetry over mobile phone net?

Not as far as I know, you might be the first to come up with this idea here ! and it does sound interesting !
There is forum user Pawel who had an idea of registering his glider on online service tracking all gliders in the area, but that's not using GSM trans-receiver, but just simpler 900Mhz radio.

An interesting thing would be using GSM instead of GPS to increase the accuracy of position estimates. I recall I saw some papers about this.
For example google finds book GSM-based Positioning: Techniques and Applications By Nico Deblauwe though I don't know how it compares to GPS, each has pros and cons.
GPS accuracy suffers when close to buildings (multipath reflections), GSM can't be used far from (maybe multiple) towers.