Immediate cut-through is enabled. It still has the delay.

It almost seems like it's something to do with the PBX trying to decipher what is being dialed, or caching the digits.

I can pick-up a phone and dial 444 as fast as I can, while listening to the trunk with a Test Set, and the first two digits immediately pick-up the line, but I can count one-thousand one, one-thousand two, before the last 4 is heard.

It's not the end of the world, but it's just inconvenient. It's also weird that it started happening after the upgrade.