Does SQL Server's serializable isolation level lock entire table

Me and a colleague of mine discussed the implications of use of the serializable isolation level. He said it locked the entire table, but I disagreed to that telling him it potentially could but it tries to apply range locks and it doesn't apply true serialization as explained here: The Serializable Isolation Level . I can't find anything in the docs either for the "locks entire table": SET TRANSACTION ISOLATION LEVEL . The doc states a bunch of things regarding range locks, so in theory you could lock the entire table by simply having a range lock that locks the entire range of possible values in the table, but it doesn't lock the table. Am I completely wrong here? Does it in fact lock the entire table (or tables)?