One of the multiple providers of {HEAD ~ services} is then selected by generating an access code corresponding to one of the service providers in accordance with a predetermined algorithm which provides a desired distribution of usage by {TAIL ~ the subscriber} of a plurality of the service providers 
One of the multiple providers of { HEAD ~ services } is then selected by generating an access code corresponding to one of the service providers in accordance with a predetermined algorithm which provides a desired distribution of usage by { TAIL ~ the subscriber } of a plurality of the service providers
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH