When was the first cellphone developed?
History of mobile phones
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The GSM Association (GSMA) followed suit on 17 February 2009,[53][53][54][55][56] and on 22 April 2009, this was further endorsed by the CTIA – The Wireless Association,[57] with the International Telecommunication Union (ITU) announcing on 22 October 2009 that it had also embraced the Universal Charging Solution as its "energy-efficient one-charger-fits-all new mobile phone solution," and added: "Based on the Micro-USB interface, UCS chargers will also include a 4-star or higher efficiency rating—up to three times more energy-efficient than an unrated charger."[58]