The cost of calls to different countries/cities is determined according to rate tables that come from VoIP User’s own PSTN line provider(s), so costs vary over time as they do for fully commercial international telcos. Such variations are affected by changes in international currency exchange rates, commercial negotiations between large international carriers and commercial policies. Where VoIP User varies from a commercial telco, though, is that the intention is not to make large profits from connecting calls, but rather to broadly break even. This methodology is frequently referred to as "minute neutral".