DTMF emulation time (Asterisk 13.5.0)

Hi everyone! I’m operating an asterisk 13.5
I want to know if there’s a way to change DTMF emulation time or min dtmf duration.
This is because i want to send alarm systems through asterisk and there’s an issue with some protocol when transmitting a code, ContactID must have 50ms tones and my asterisk emulate 80ms to queue…
Here is an image to understand what i mean http://www.voip-sip-sdk.com/attachments/579/contact_id_protocol.jpg

If it is that fussy, you will need to use Playtones, instead. Make sure that only G.711 codecs are used between you and the alarm centre and that no-one on the way attempts to convert inband tones to out of band signalling.