Mobile dating websites, in order to increase the opportunities for meeting, focus attention on users that share the same social network and proximity. Some companies even offer services such as "homing devices" to alert users when another user is within thirty feet of one another. Some systems involve bluetooth technology to connect users in locations such as bars and clubs. This is known as proximity dating. These systems are actually more popular in some countries in Europe and Asia than online dating. With the advent of GPS Phones and GSM localization, proximity dating is likely to rise sharply in popularity.