I have an IPO 406 with IPOffice Manager 5.2(55). I have 2 4424D phones, 2 5420's and 13 5410's. I have been asked to get headsets to put on the 4424's. From what I have been able to find (mainly in Merlin related documentation), I am supposed to program a Headset Hangup button for the phones in order to activate the ability to use the headsets. All I see in the IPO button programming is the possibility of Headset Toggle...nothing for Headset Hangup. Is that the IPO equivalent that will work for these phones ?