Would these work?

[JonathanMC]

Just asking if there would be any problem getting this jack for a headphone/composite in jack? I don't see why not.
http://www.taiwantrade.com.tw/MAIN/en_f ... ome_soon=0" onclick="window.open(this.href);return false;

Also, would these jacks be compatible for each other and would they work for a breakout box?
http://www.allelectronics.com/make-a-st ... HT//1.html" onclick="window.open(this.href);return false;
http://www.shutterstock.com/pic-3797011 ... -data.html" onclick="window.open(this.href);return false;

[Snow_Cat]

you should have no problem finding a 3.5mm jack, it is readily availble from a variety of suppliers.

The RJ12 (telephone) jack and RJ45 (ethernet) plug are incompatible (by design).

You will need a matching pair or a hacksaw to make them fit together.

[JonathanMC]

Thanks for your reply. I think these would work, right?
http://www.summitsource.com/product_inf ... ts_id=9734" onclick="window.open(this.href);return false;
http://www.king-cart.com/cgi-bin/cart.c ... e=HWS11065" onclick="window.open(this.href);return false;

[Snow_Cat]

Yes, they are both RJ45 and therefore compatible.

Though the per-unit price may be lower from each source, you might save on shipping by ordering from a single distributor like Digikey or Mouser, or even by finding an electronics surplus supplier (depending on order size).