I am going to buy A6 GSM module for connecting to my Raspberry PI and making a little research here. Will I be able to power up this module purely from PI or external power source is a must?
A6 data specification says it requires from 4.9 to 9 volts. Can it be powered up, for example, from GPIO port, which seem to be provide 5V? Some sources say about 5V battery, but maybe it's just a a recommendation?
I am totally newbie in electronics and had no experience with PI before. I have Raspberry PI 2 model B revision 1.1.
UPDATE: I found out that module specified in my first link is not actually a SIM900 module so I corrected the title. It is A6 tagged as a replacement of SIM900 and seems to be based on GSM/GPRS A6 chip.
Also in the web I found several modifications tagged both as SIM900 and A6 (1, 2, 3), and all of them have different power consumption (1.3mA, 1.5mA, 2mA). As I have no particular preference in one GSM module over another during the purchase, opinions on any of them are appreciated. Real experience is highly appreciated.