[Freeswitch-users] reINVITE with a=sendonly

I'm using FS for PTT (Push-To-Talk) services. To start talking FS sends reINVITE (I use "uuid_media_reneg <_uuid>" command for this). I need to add "a=sendonly" to this reINVITE. How it can be done? With best regards, Shumaev D.A., programmer @ KBR Ltd.