The SX-200 and its bigger sibling, the SX-2000, were Mitel’s cabinet-and-card digital PBXs. Their descendants became the MiVoice line.

What callers heard

Music on hold needed a separate Music-On-Hold/Paging module (the SX-2000 used a DNIC Music-On-Hold/Pager unit) fed by an external source. Mitel treated paging and hold music as one “external audio” feature. No card or no source meant no music.