With one telephone line, would call forwarding be an issue?

["David" <this@xxxxxxxxxx>]

In a residential setup where there is just one telephone line, would
having the phone company activate call forwarding on that line
interfere with the operation or maintenance of the alarm system?
Put another way, do residential alarm systems actually monitor
and respond to incoming calls in any way or for any purpose such
as remote diagnostics, testing, or what have you?