SIM900A not responding to AT commands. - Raspberry Pi Forums

hey,

think wired sim900a correctly rpi, however, everytime issue "at" command using minicom on /dev/ttyama0, don't answer (http://i.imgur.com/mpg9vm0.png).
led blinking @ 64/800 means don't have network, @ should still work, right?
tried changing baudrate no luck.

i'm not sure i've done wrong.
kinda scheme wiring:

sim900a->rpi
gnd->gnd
txd->gpio14
rxd->gpio15

, power shield:
gnd->pi's gnd
vcc->random iphone cable (plugged pi).

think must wiring power shield well...

if can help, i'd appreciate sure!

thanks!

what power source using(voltage/amps)?
having problem power , sim900 dropping network.
first thing should check.

raspberrypi