Instead of putting a cell phone near a PC speaker :
Is there a way to stream outgoing sound from PC (the so called Stereo Mix in Windows) to a cell phone input (an iPhone for example) and then to a 3GP call ?
I did the same thing in college to annoy people in the dorms with funny sound boards. Calling people with a Mister Rogers sound board was always hilarious.
anyways, you can easily coble together a 1/8" headphone jack to a headset plug (with mic input) that is meant to plug into a cell phone. I'm not sure if there is a commercial product available but I know I made one in about 5 minutes with parts from radio shack.
Yes, but we need more details to know what to recommend.
If you are going to be using this a lot, you can use something like this http://www.buy.com/prod/jk-audio-daptor-2-dap2-wireless-phone-audio-interface-for-use-with/q/sellerid/22583914/loc/111/219845839.html
Depending on the phone, you can also sometimes just use a standard 1/8" cable.
The first half can be done with Wifi2Hifi, the second half isn't something I've ever heard of. Either use a second device, or turn the volume up so the microphone of the same iphone can hear what the speakers are doing (unless iOS mutes it for the call, which is likely).