ZID Controller voiced concerning the lack of back up frequencies; noting the lack of same was the weakest part of their safety system.

Narrative

The BOB Sector owns FL320 to FL350 and is commonly combined with the CRW Sector; FL240 to FL310. When we De-combined the positions for normal traffic; the BOB Sector frequency was immediately reported as being of poor sound quality. Within a minute it was reported as almost unusable. We attempted to get an alternate frequency to it quickly; but the area with that new frequency couldn't give it up right away. The BOB Sector frequency was lost at that time; and an aircraft had to relay control instructions to prevent an operational error. The frequency continued to be out of service for almost four days. Now; the BUEC for the CRW Sector; which is controlling the BOB Sector as well; is out of service. We have one frequency; main and standby; only; for two sectors; for days; without any relief in sight. J6 runs right through these sectors; so major traffic restrictions have to be put out to cover the volume of traffic. BOB is normally split out about half the day or more; for average traffic volume. Aircraft are dropped to FL220 instead of FL340 or above; due to frequency and volume restrictions. The volume requires a tracker to be at the position for more than an hour; with a major weather frontal passage through the sector that caused every aircraft to deviate. I know the technicians are working on it; but we are restricting traffic for days on end; for the loss of one frequency. We need another; spare frequency; for ARTCC's; period. It is the absolute weakest part of our safety system to have no backup frequencies for these events. Simply inexcusable; we need back up; spare frequencies; period.