Money expert Martin Lewis says mobile phone customers can save money by sending a text to a 5-digit number.

Financial guru Martin Lewis is encouraging individuals to send a text message containing a five-digit code in order to reduce their mobile phone bills.

Martin Lewis tells 14m people with phones to text 5-digit code The Money Saving Expert founder warned that most people are "massively" overpaying.

The circuit is quite old using CMOS 4081 with 4 ‘AND’ gates to hardwire the access code. [myvideoisonutube] references [Ron’s] “ Enhanced 5-Digit Alarm Keypad ” schematic for this build ...