I had problems with a bulk order of 12 phones. Wurtec had me replace mics on all phones which did not work. The final solution was Wurtec replaced all phones with resistor changes to reduce feedback. This was very discouraging after phones were installed TWICE so I started to use KingsIII phones and have been much happier so far. The symptom of the failing Wurtec phones was that you could start a conversation but a few seconds in it would start to scramble your words and make the convo in the car no good but ok on the office side.. I had these phones on several different building phone systems and had no luck until I got the revised phones from Wurtec.

Same problem in SD. 4 bad phones recently. Wurtec denied knowing anything about any problems lately. Funny what you can find on the internet... Same symptoms. Start conversation and a few seconds in communication is lost. These were all transformer powered phones. Funny thing is they all worked fine on battery backup. Soon as you plugged transformer in it would fail.

I've had some problems with mics and speakers failing and some phones boards just failing as well.