I was wondering if there is a way of making the Sv9100 send DTMF tones on all calls and not just external. I have a Fanvil i10 door intercom that needs DTMF tones to unlock the door. The phones (UT880) i am using do not have a way to enable the DTMF tone all the time. At the moment when i make a call to an external line i can send DTMF tone but when i do an internal call they will not. I was wondering if there are any setting in the SV9100 that i can change to enable tones all the time. I can confirm that the Fanvil i10 is working correct as i have a couple of DT820's that i have set in the menus to enable the DTMF tone. The DT820 will open the door.