About: http://webisa.webdatacommons.org/291573677

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Some of the service providers sell different types of vouchers, which differ from each other e.g. in the number of call units and the time the call time bought is valid.
http://www.w3.org/ns/prov#wasQuotedFrom	freepatentsonline.com