TLS & SRTP support on Cisco spa303

Hello Im working with cisco and grandstream telephones, and I read something about the configuration that should be configure on the FreePBX, also I generate the certificates for those telephones (extensions); some information was clear and works for me, I read something about configuration over Blink Softphones… but I´d like to work with hardphones, and complete the installation, and try to configure the certificates on cisco and grandstream telephones.

Does anybody or someone get trought those telephones and made an encrypt calls, working with TLS and SRTP, with softphone blink works everything fine; or someone should works with cisco telephones ( eg: cisco spa303) or grandstream (eg: GXP2200)

Thank you.