My answer applies to all vtc systems, not just Lifesize and/or Blue Jeans:
If they are dialing the call from a Crestron touch panel they usually want to type in the bridge access code from the touch panel as well so I always make a way for them to send DMTF tones from the same keypad... either a button to switch to DTMF or, depending on the codec and which module you are using, simply watching for a call to be connected and then switching over to DTMF; this can be a drawback though if they need dial multipoint calls at times too.
The short answer is yes, I normally incorporate DTMF keys on the touch panel but it kinda depends on the hardware and the client as to how I do it.
