Cell phones, especially iphones do put out a signal for a short range "to be discoverd", to have a good wifi signal you need to at least have an RSSI of -67 (some say 69 -beautiful number-, but I keep to 67). Iphones take that down to -72 in close range if you're already on the edge, which you shouldn't be because you are on stage and your receive is within 10 mdoeof you, very rarely 20 if it's the biggest of stages... but even then, respectfully, your statement does not make sense... since line 6 uses the same 2,4 ghz wifi tech up to 14 channels (11 or them are legal in europe so you could theoretically fix your channel to 14 and there will be NO possibility of interference wha so ever, since EU wifi equipment only goes up to 12, and we can't even use 12) it used it's own encryption, it can't be discovered by other networks, as far as wifi scanning unit it doesnt' exist.... you might see a line (mux) but you won't be able to identify it. That being said.... other line 6 devices WILL interfear, and they made a problem out of this by not having sepperate groups of devices as say, guitar wireless systems using a different strain of encryption or identification.... it interferes with my reception unit.
Also that being said, I've gigged with mine numerous times, and yes, I also suffered dropouts... I wanted to shell out for a UHF mic but you just never know when they are going to take the available frequentie away in any given country, even if you buy the most widely equipped frequentie range mic that will cost you 700 up to 1500 usd, they can lollipop you up tomorrow so the "more and more unreliable 2,4 ghz" is your only choice left to even have the most remotely safe solution.
Such a pitty they never thought of going 5.1 ghz... now that 5 ghz wifi is out with over 120 channels to choose from it should almost be idiot proof, make it 5.1 specifically for musical gear and every problem is solved... after all these years I still can't understand why that has not happened yet.