We using mobile phones to send audio signal from mixer. Here is the cable pinout.

                |‾‾‾‾‾‾‾‾‾‾‾‾‾
/‾\/‾|‾‾|‾‾|‾‾‾‾| Headphone Jack
\_/\_|__|__|____| Samsung Phone
 |    |  |  |   |_____________
 |    |  |  |
 |    |  |  |      C1    100 nf
 |    |  |  |_________||__________\ Mic     | Headphone Jack
 |    |  |       |    ||          / Line-in | Audio Mixer
 |    |  |      |‾| R1 
 |    |  |      | | 1.4 kOhm
 |    |  |       |
 |    |  |_______|________________\ Gnd     | Gnd Headphone Jack Audio Mixer
 |    |                           /         | Gnd Insert Line Audio Mixer
 |    |
 |    |___________________________\ Right   | Insert Line
 |                                / Out     | Audio Mixer
 |
 |________________________________\ Left    | Insert Line Left
                                  / Out     | Audio Mixer