Those are the actual SMDI codes for lamp on and lamp off. You can send the same string with a terminal program and it should also activate and deactivate MWI. It's pretty easy to read, OP for on, RMV for off, followed by the :MWI then the SMDI extension number.
If Unity is sending the code but the switch isn't responding to the request, that's likely a problem in the phone system. If you have a loopback tester, you can do a loop back test to rule out a defective serial port or cable, but if it were a hardware problem you'd probably see the issue more frequently.
What you can do on the Unity is make sure you don't have any bogus lamp codes going out (disable MWI for virtual subscribers that don't have physical phones), and lower the number of retries if you see multiple instances of the same code going out each time. Some phone systems will flush their MWI queues if they get overloaded with lamp requests.
Oddly, I didn't see a place in the SA where you could set the MWI retry count (although you can do this for all the notification devices), but it's possible to modify the retries with the edit switch utility or in the switch file itself.
However, in this situation it sounds like the defective behavior is coming from the phone system, since Unity is doing its job by sending the lamp request.
Scott Morgan
Cisco Systems TAC
