Ya no se me ocurre mas que cheques con estos códigos :
#*3282# = Data Activate/Deactivate
#*4760# = GSM Activate/Deactivate.
#*2527# = GPRS switching set to (Class 4, 8, 9, 10)
#*7524# = KCGPRS: (FF FF FF FF FF FF FF FF 07)
#*7562# = LOCI GPRS: (FF FF FF FF FF FF FF FF FF FF FF FE FF 01)
#*3476# = EGSM Activate/Deactivate.
#*4760# = GSM Activate/Deactivate.
#*7288# = GPRS Detached/Attached.
#*7287# = GPRS Attached.
#*3270# = DCS Support Activate/Deactivate.
espero que puedas resolver tu problema.