Nextel comm 7520 ユーザーズマニュアル

In aTalkgroup call, you can communicate instantly with a group of people 

that you have previously set up as a Talkgroup. A Talkgroup is a 

predefined group that has been provisioned by Nextel or an account 

administrator. To make or receive a group call, you must be a member of 

the Talkgroup and your service provider must support group calls.
Talkgroups are limited by network (fleet) and local markets. They can 

accommodate groups up to 100 members in the local market. 
Before you can make or receive Talkgroup calls, a Talkgroup must be 

established. After the Talkgroup is established, you must join the 

Talkgroup. For more information, call Customer Care at 800-639-6111.