Sharing Iphone headphones with Iphone and RT - Will this damage the phone?

[TURSTY]

Hi all,

I snowboard a lot and use my iPhone 4s for music and a RT to keep in touch with friends on the MT.

I have a helmet with integrated speakers that I use for the music.

I can get an adaptor that allows two 3.5mm jacks to plug into one set of headphones and share the headphones with the RT when people talk. The problem with this however is that whatever signal comes from one device, will not only go to the speakers, but also the other device thats plugged into the cable.

Is the signal from the RT likely to damage the iPhone if it goes into it?

The wireing will be: 3.5mm from Iphone to Iphone remote cable (has play, pause, volume and mic) then to T adaptor. 3.5mm from RT to other side of T adaptor. Top of T adaptor to headphone speakers.

Thanks.