Panasonic TDA has the best wireless solution of any system I know of, main points being coverage, ease use (ie- buttons for functions instead of complicated codes) and a low price point for the components. Easy admin, IP options, PC console for recption. Stable software, does not need to be shut down for regular maintenence.
The wireless could be cell station based or just use the basic system cordless 7896, depending on the size and construction of the structure.
Either way the ease of use is tops.
If there is no Quality dealer in your area--
Forget about it!
As for self programming-- many systems now have extensive user programming. Have put in many computer based systems that boast self admin, and still get lots of calls for help. yes the end user can do it , but after the initial setup may not use for months and then can,t remember how, or get lost as to how to acomplish a task. A good dealer will be able to swap extensions and make any change right down to a speed dial button on any phone remotly
for much less than on site service. The only reason for on site visit would be to install new wire or other hardware or annual maint checkup.
Sorry, here,s the soapbox back>>