How to find SQL server listening port

1. Value of error log file you want to read: 0 = current, 1 = Archive #1, 2 = Archive #2, etc…
2. Logfile type: 1 or NULL = error log, 2 = SQL Agent log
3. Search string 1: String one you want to search for
4. Search string 2: String two you want to search for to further refine the results
5. Search from the start time
6. Search to end time
7. Sort order for results: N’asc’ = ascending, N’desc’ = descending

xp_readerrorlog 0, 1, N'Server is listening on'

Using other option

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

DECLARE @value VARCHAR(20)
DECLARE @key VARCHAR(100)

IF ISNULL(CHARINDEX('\', @@SERVERNAME, 0), 0) > 0
	SET @key = 'SOFTWARE\Microsoft\Microsoft SQL Server\' +    @@servicename +    '\MSSQLServer\SuperSocketNetLib\Tcp'
ELSE
SET @key = 'SOFTWARE\MICROSOFT\MSSQLSERVER\MSSQLSERVER\SUPERSOCKETNETLIB\TCP'
SELECT @KEY as [Key]

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

SELECT 'Port Number : ' + CAST(@value AS VARCHAR(5)) AS PortNumber