The Inter@ctive Pager 900 was a clamshell-type device that allowed two-way paging. In this measure, participants are given a beeper/pager that will randomly ring throughout the day. It was a mobile phone, pager, fax machine, and PDA all rolled into one. Pager, an instant messaging service that was renamed Yahoo! It was the first watch/pager able to receive alphanumeric messages. He takes his pager and phone apart and finds a tracking device. The alarm can be performed by different alarm systems, such as by sirens or pager. This can result in pager messages being delayed or lost. Timex and Motorola introduced Beepwear in 1998, a watch with an integrated pager. The first telephone pager system was patented in 1949 by Alfred J. Gross. In 1995 Motorola introduces the 2 way pager. One form is the "cat page", simply piped to the pager for display. The next device to be released was the Inter@ctive Pager 950, on August 26, 1998. A '7' was prefixed to existing pager service numbers. A popular cross-platform terminal pager is more.