Reduce 3.5mm 4-Conductor Plug to Fit into 2.5mm TRRS Jack
Plug your iPhone Earphone into a Standard 3-Conductor Jack
Amazon.com: Fancasee 4 Pack 3.5mm Replacement Repair Plug Jack TRRS 4 Pole Stereo Male Plug 1/8" 3.5mm Solder Type DIY Audio Cable Connector for Headphone Headset Earphone Microphone Cable Repair : Electronics
Phone connector (audio) - Wikipedia
Amazon.com: Fancasee 2 Pack Replacement 3.5mm Female Jack to Bare Wire Open End TRRS 4 Pole Stereo 1/8" 3.5mm Jack Plug Connector Audio Cable for Headphone Headset Earphone Microphone Cable Repair : Electronics
How to Hack a Headphone Jack
Amazon.com: Fancasee 2 Pack 6 ft Replacement 3.5mm Male Plug to Bare Wire Open End TRRS 4 Pole Stereo 1/8" 3.5mm Plug Jack Connector Audio Cable for Headphone Headset Earphone Microphone Cable
Headphone Jacks and Plugs: Everything You Need to Know - Headphonesty
Making a [4-Pole TRRS to 3.5mm Stereo & Mic Adapter (Male to 2x Female)] from an iphone headphone split… | Earphones wire, Electronic schematics, Headphone splitter