Knowing PBX system costs requires understanding how the system works and what associated charges will be incurred. In basic terms, the upfront and maintenance expense of a standard PBX will be great but typically come without much in the way of per-minute charges. A hosted PBX will have a small per minute charge but virtually no or very little initial set-up costs and no maintenance fees (typically the better choice for small businesses).
For companies that have large toll-free call volume, the comparison looks like this: