Over on a Voice Ops listserv, some ITSP's are discussing blocking access to free conference calling services. One, I'm not certain that is legal. I think a complaint to the FCC could make an ITSP's day go south.

Two, bad press from blocking could lead to negative branding. If you subscribe to the theory that all press is good, you are mistaken. A small ITSP without much branding could be looked upon very unfavorably by the marketplace.

The other part of the discussion is upstream capacity issues to these exchanges. For example, ITSP A might not be able to complete the call to the free conf service line because their upstream carrier (say, Level3) doesn't have enough capacity to that exchange/rate center to complete the call. So it may not be the ITSP's fault entirely.

One ITSP has tried to educate his marketplace about free calling sites. (see here). Speakeasy, now owned by the MegaPath/Covad combine, blocks by area code and prefix. And of course Sprint and AT&T have sued over this, calling it traffic-pumping.

This is yet one more example of how telecom is a business of arbitrage. Moreover, if the FCC would just rule on Inter-Carrier Compensation after its years of study, this would not be a problem.

Note: I use freeconference.com and other services.

UPDATE: in June 2007 the FCC made a declaratory rule and order on call blocking.