The JK Audio PBXport Rackmount Digital Hybrid is a professional audio interface that provides "talk show" quality audio from a PBX, ISDN, or analog telephone system. It works by connecting between the telephone base and the handset, allowing microphones and mixers to interface with the phone system while eliminating the common audio bleed found in analog hybrids.The 1U rack-mount unit features balanced female XLR inputs for mic or line level signals, a balanced male XLR output containing only the caller's voice, and a separate balanced male XLR mix output. It includes a 1/4" headphone jack on the front panel with a mix monitor level control. A crucial feature is the three-position Handset Type switch (Electret, Dynamic, or Carbon), which ensures compatibility with the different microphone types found in various PBX phones.