The cd player must be in pairing mode. Look at the directions that came with it. Once it is in pairing mode the iPhones will see it click on pair device and enter the code the instructions tell you to. It is usually 1234 or 0000. If it didn't have a pairing mode then anyone driving next to you could pair with your cd player and play their music on your radio. Most Stereo/CD players with Bluetooth have a button on them that looks like a telephone. push and hold that button until the screen says pairing then look on the phone find the device under bluetooth settings and select pair device. It will then ask you for the pin number which is usually 1234 or 0000.
Try turning off the bluetooth and then back on on the iPhones. If that doesn't work try resetting the phones by holding down the home button and the sleep button until the Apple logo appears. Then open up bluetooth settings and turn on Bluetooth again. Keep in mind once the CD player connected with the old sony phone it stopped being in Pairing mode and will have to be put in pairing mode again to pair with the iPhones. it also will only stay in pairing mode for about a minute give or take a few.