(Reuters) - Verizon Communications Inc started taking preorders for Samsung's first 5G smartphone in the United States on Thursday, and said it would launch the high-speed wireless service in 20 more cities after Chicago and Minneapolis. Verizon said customers pre-ordering the device can get up to $650 off on the Samsung Galaxy S10 5G if they switch to its network and trade in their older phones. The Samsung 5G phone, exclusive to Verizon for a limited time, will be available in the telecom operator's stores from May 16 with a starting price of $1,299. Users in Chicago and Minneapolis can currently use Verizon's 5G network by using a Motorola Z3 mobile and a 5G "Moto Mod", a physical magnet-like attachment for the phone. Washington DC, Houston, Dallas and Boston are some of the cities that made it to Verizon's 5G list. Rival AT&T launched its 5G network in 12 U.S. cities in December. However, its network is available only to consumers using a mobile hotspot device, not on 5G phones. (Reporting by Sayanti Chakraborty in Bengaluru; Editing by Saumyadeb Chakrabarty)