What - exactly - is this component

[SWRmeter]

This component is placed in the signal path next to a multi-band GSM antenna.
It seems to have 3 terminals - 1x GND and 2x in signal path.
I suspect it is some sort of bandpass filter, but cannot locate the exact details anywhere.

Any help ?

 

[SWRmeter]

To add to the above information, here are side elevation close-up pics. I
t sure looks like a ceramic filter structure, but which one ???
Dimensions are 11mmx 7mmx 3mm

Also to add that the frequency bands are as follows i this attached table.
Note that this assembly ALSO has GPS and GNSS circuit on board, but they are NOT part of this signal pathway.