In fact, such is mandated by most governments so they can establish a wire-tap.
https://ssd.eff.org/book/export/html/51 is a short read about this and no spy software needs to be installed.
You can also research the USA FBI's "going dark" program.
Why is there any doubt here?
can anyone using same wifi network as I do and who's really good in networking & hardware read my text messages as well as access the data in my iphone 4? A friend claims that my BF was able to see my text messages even though there was no monitoring/spy software installed on my iphone