dual-SIM phone

A dual SIM phone is a mobile phone, typically a smartphone, with the capacity to use two subscriber identity module (SIM) cards. 

A SIM card is a smart card that stores data for the owner, including user identity and preferences, location and phone number, network authorization data, personal security keys, contact lists and stored text messages. To transfer the data to another phone, the user just has to take the SIM card out of one phone and insert it in the other. 

Dual SIM phones are used for a number of purposes, including the following: 

• Two people can share a single phone, each with their own phone number and data stored on separate SIM cards. 
• In a BYOD environment, employees can have their personal numbers and data separate from those for work. 
• People can have a business number and a personal number on a single phone rather than dealing with separate handsets. 
• Travelers can acquire a local SIM card to avoid roaming charges while still being available at their usual number.