No sorry, DTLS is a totally separate feature. That requires devices end-to-end to support such encryption. What you are most likely looking for is TLS over SRTP. You can't really do this over the GUI; only enabling an extension using SRTP will work, though I've never tried it.
Read my guide again above and let me know if you have questions. I'll do my best to help...can't promise anything in a timely manner.