I have a dual cabinet KXTD 1232 with a TVS 120 voice mail. Up to this time they have not used any mail boxes and now they want them. When I call internally the system works fine getting to the mailbox on a no answer or busy. The problem is when calling from the outside, there is no response on a no answer and "not a valid extension" on a busy. The KXTD is about fifteen years old and previously uses a call express system. The cos and voice mail ID is programmed with just the extension number in the KXTD. Also, if I transfer a call from the outside the voice mail does pick up. Hope that's enough info.