... -TSRS-232 Interface, Siemens TC35i module inside, 900/1800Mhz Dual band. +5VDC, +7. 5~26VDC Optional. GPRS MODEMH6221-WRS-232 Interface, Wavecom ... module inside, 900/1800 Dual band. +5VDC, +7. 5 ... or +7.5~26VDC. H6221-M2RS-232 Interface, Moto G24 GPRS module inside, 900/1800 Dual band. Either +5VDC or +7.5 ...