SINCODA 2-Way RJ11 6P4C Telephone Plug to RJ11 6P4C Socket Adapter and Splitter for Landline Telephone *Sometimes the jacks are recessed in the case of the VOIP unit.
*These splitters works great in this situation because it gets the splitter away from the jack a bit with the flexible cable.
*It can be easily installed on the phone and handset without any tools.
*Does not affect the sound quality because of the advanced technology and high-quality materials.