Truename magic when used is treated as a spell like ablility. Though it requires careful pronunciation, it does not involve any hand movements or spell components. Even if a truename magic user is silenced, her spell like ability's chance of failure is only 20%.
List of creatures that use truename magic:
There are probably many other humanoids in the world of Eberron who use truename magic, however it is not particulary common. The only base class that uses truename magic is a truenamer.
Tome of Magic (book) page 191