GSM4KCR-1S/4G. The Videx 4000 Series GSM4KCR-1S/4G “entry-level” surface mounted audio kit is a totally self contained GSM door entry system kit complete with keypad. This keypad has 3 codes, 2 changeover relay outputs and an override input. It can, furthermore, be programmed from 1-99 seconds or latching output. This kit also includes a door panel, Psu & antenna, requires only a Sim card, and can be programmed by either SMS or PC Software.. 1 way surface audio gsm kit with keypad. Diversion to second number when first number is busy / not answering. Dial open, balance check & signal strength checking facility. Totally self contained (only requires an external power supply and antenna)