Outsourcing it is very interesting. Many big companies use outsourcing in their business. But there is also such thing as outstaffing https://qubit-labs.com/outsourcing-vs-outstaffing/ It is not the same, but it is also a good solution.

Yes, I have some experience with such company as NixSolutions. You can easily get more imformation about their QA service here http://www.nixsolutions.com/services/qu ... -services/. They are professionals and I can recommend them.