TSQL to find if server is listening on dynamic or static port

Using TSQL, how can I find if the MS SQL server (any version) is configured to use static port or is it using dynamic port?

Script i am trying to use:

DECLARE @TcpPort VARCHAR(5)
        ,@RegKey VARCHAR(100)

IF @@SERVICENAME !='MSSQLSERVER'
    BEGIN
        SET @RegKey = 'SOFTWARE\Microsoft\Microsoft SQL Server\' + @@SERVICENAME + '\MSSQLServer\SuperSocketNetLib\Tcp\IPAll'
    END
    ELSE
    BEGIN
        SET @RegKey = 'SOFTWARE\MICROSOFT\MSSQLSERVER\MSSQLSERVER\SUPERSOCKETNETLIB\TCP\IPAll'
    END

EXEC master..xp_regread
    @rootkey = 'HKEY_LOCAL_MACHINE'
    ,@key = @RegKey
    ,@value_name = 'TcpPort'
    ,@value = @TcpPort OUTPUT

EXEC master..xp_regread
    @rootkey = 'HKEY_LOCAL_MACHINE'
    ,@key = @RegKey
    ,@value_name = 'TcpDynamicPorts'
    ,@value = @TcpPort OUTPUT

SELECT @TcpPort AS PortNumber
        ,@@SERVERNAME AS ServerName
        ,@@SERVICENAME AS ServiceName

You can determine which port an instance is using from the error log but not whether its static or dynamic.

EXEC xp_readerrorlog 1, 1, 'Server is listening'

Alternative would be to read from the registry via xp_regread.

DECLARE 
    @StaticPort NVARCHAR(512)
    , @DynamicPort NVARCHAR(512)

EXEC xp_regread
    'HKEY_LOCAL_MACHINE'
    , 'SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL.1\MSSQLServer\SuperSocketNetLib\Tcp\IPAll'
    , 'TcpPort'
    , @StaticPort OUTPUT

EXEC xp_regread
    'HKEY_LOCAL_MACHINE'
    , 'SOFTWARE\Microsoft\Microsoft SQL Server\MSSQL.1\MSSQLServer\SuperSocketNetLib\Tcp\IPAll'
    , 'TcpDynamicPorts'
    , @DynamicPort OUTPUT

SELECT
    @StaticPort AS StaticPort
    , @DynamicPort AS DynamicPort

StackExchange Database Administrators Q#6872, answer score: 9