I see this board has a current surge when running using the GSM module and it is recommended to use the battery.
But I'm having a little trouble finding a lipo battery with a capacity greater than 850mAh. can i use a li ion battery which tends to be easier to get and cheaper? is it safe for my board?
IMHO with a proper power supply (not over the USB port but over the pins)you don't need a battery. If you want to use a battery IMHO you can use a smaller bat.