On behalf of GOOG-411 (A Google Service) users in the United States I contacted Google Corporate Offices regarding the block of Payphones from accessing the service and below is a copy of the response I received from Google Corporate Offices.

We are writing in response to your letter of January 29th, 2008 regarding the complaint received from Benjamin Kerensa.

We understand that Mr. Kerensa has had some difficulties using the GOOG-411 service from payphones. GOOG-411 is a free directory service offered by Google Inc, which is currently only released in development mode (beta). Due to the fact that the GOOG-411 service is free and not advertising supported, the service does not currently allow access from pay phones in the United States. A technical error allowed access from some pay phones at the time of launch in April 2007. The error has since been fixed.

The GOOG-411 service was never promoted or advertised as being specifically available from pay phones. Further to this complaint, Google has revised the GOOG-411 pages to be clearer in this regard.

See, for example, http://www.google.com/goog411/about.html.In terms of customer support, since the product is in beta mode, Google can only offer limited support in the form of the Google Mobile Help Group which is monitored by members of the Mobile Team.GOOG-411 help is also available from the GOOG-411 Google group at http://groups.google.com/group/goog411?hl=en, where this issue of "pay phone access" was discussed and officially answered on May 17, 2007 (thread).

We apologize for any confusion Google may have caused Benjamin K. We assure him that we are constantly working to refine and enhance our products to bring all our users the best experience possible.

Sincerely,
Gosia,

The Google Team

Based on my complaint which was received by Google the Goog-411 website has now been updated to clarify where specifically this service can be used from which was not clear previously.