FWIW it is always the PMS. The iPocket will work as programmmed. Yes if able to do direct ip, that could be better, but then again if there is an issue it is the PMS most likely.
^^^ This... Assuming there isn't connectivity issues to the iPocket/serial port itself, if there are PMS issues, it is
ALWAYS on the PMS system side. Since the release of the SX-200 ICP around 2000 or so, I have installed several hundred of the iPocket232 units, literally, and I have never seen a single one fail (a couple power supplies have failed though, out of hundreds). The iPocket devices just work, never seen one lose it's config or connection without outside influences, and Mitel is one of the originators of the PMS interface, it is rock solid on that end too.
There is a PMS Emulator program available from Mitel, all I do anymore if a site insists that the problem is on our end, is go out there with a laptop, disconnect the serial cable from the PMS server, connect it to the laptop with the PMS emulator app, and prove it works, which it always does, show the customer, reconnect the cable and tell them to call their PMS vendor.
Sorry if this sounds like a rant, I literally just went through this and was venting just a little.
Whew... I feel better now.