Google Directions API Request Limit

The URL http://code.google.com/intl/lv/apis/maps/documentation/directions/ includes the following: -

<P → Limits of Use Using the Google Directions API is subject to a request limit of 2500 requests per request per day.

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This applies to each handset (i.e., each phone is allowed 2500 requests per day) or for the application as a whole (i.e. only 2500 requests per day are allowed for this application, regardless of the number of incoming calls), I know That Premium Service allows 100,000 requests, but it's a bit expensive.

Thank you very much in advance

Floor