@@MAX_CONNECTIONS (Transact-SQL)
SQL Server 2005
Returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured.
Transact-SQL Syntax Conventions
The following example shows returning the maximum number of user connections on an instance of SQL Server. The example assumes that SQL Server has not been reconfigured for fewer user connections.
SELECT @@MAX_CONNECTIONS AS 'Max Connections'
Here is the result set.
Max Connections --------------- 32767
Reference
sp_configureConfiguration Functions