I'm running into an issue with my 'D1232. I'm programming it using the appropriate Panasonic DOS software, and I have initialized it to factory default settings. When I attempt to set a four-digit extension number for an arbitrary jack, I keep getting "SAME EXTENSION" error messages. The manual indicates that two jacks can't have the same extension number, and I'm pretty sure I followed that. The manual mentions four digit extensions, but was cryptic as to the numbering scheme. (As an example: Leaving everything else to default values, I tried setting the extension number for Jack-1 to 5001, and still got the SAME EXTENSION error.)

Does the D1232 support four-digit extensions, and if so, what numbering scheme would those extensions need to follow?

I believe you would need to redo the entire number scheme.

But I believe not on the 4 digit.