'G' near signal icon, what does it mean?

[ImAFriendly Orange]

Hello, I have (maybe) a noobish question.
I have a new phone and it originally runs JellyBean, recently it got updated with KitKat, and since then, there appears a 'G' near the signal icon in the notification bar. What does it mean?
I have two screenshots in the attachments. One when data connection is turned on, and one when its turned off.
Thanks a lot

 

[VW Maverick]

Welcome.
What device and which carrier?

Mav.

 

[ImAFriendly Orange]

The device is a Doogee DG550 and I am on Mobile Vikings (Belgium).
The phone doesn't support all the frequencies though.

 

[VW Maverick]

It looks to be indicating which signal it is operating on.
I do not know anything about the options over there.
Wish I could be of more help.

Mav.

 

[ImAFriendly Orange]

No problem
I have seen it on more Dual-sim devices, maybe it has something to do with that?
It is also there on Huawei devices.