[Freeswitch-users] Invite with TLS when originate

I want to invite another party into a conference with TLS and SRTP enabled. Internal phones are invited by the following dialstring: {originate_timeout=30,sip_secure_media=true,context=default}sofia/default/723321@sip2.mydomain.de 72332200 Conference'. This enables SRTP but no TLS. Is there any variable I can set in order to enable TLS? set internal_auth_calls=true is meant only for configuration, hein? Also context=default doesn't succeed in this case. The call is passed to the public context. Best regards Peter