It seems that fewer and fewer recording sessions are being done under the AFTRA or SAG banner. In the biggest markets many voiceover jobs are done with a union contract, but elsewhere the session count is slowly dwindling. Sometimes a recording session can become a union session if only the talent were a bit more knowledgable and savvy.

There are several reasons you might want a session to be , not the least of which is the pay. For most of us a union session will pay more than other work, sometimes much more. But there are other reasons too.

By definition, a union session includes a contract, so session fees and how the recording may be used is already ironed out with little room for misinterpretation.

If the recording gets used in an additional way the performer makes more dough. If it goes on TV, great. Goes on cable too, more $$$.

Since there is a contract, collecting pay and enforcing reuse limits is, theoretically, easier.

http://vojo.strattonvoiceover.com/2010/10/19/union-sessions-...

Американская федерация исполнителей телевидения и радио (American Federation of Television and Radio Artists – AFTRA)
Гильдия киноактеров (Screen Actors Guild – SAG)