yes, it works for analog and IP extensions. The issue is in the Mediatrix itself, it is a SIP device so it doesn't even send the number to the 3300 until it deems that the whole number (including the 9) has been dialed. In other SIP ATA's that I have used, or SIP conferences phones for that matter, I can make this work by putting a 9, into the dial plan but the Mediatrix doesn't like the comma in the dial plan.