Connecting telephone cords together to extend the length *Connecting NTT-specification cords together → NTT-specification cord *Connecting NTT-specification cords to non-NTT-specification cords → non-NTT-specification cord *Connecting non-NTT-specification cords together → NTT-specification cord Modular jack ⇔ Modular jack
6-pole 4-core/6-pole 2-core compatible
