About: http://webisa.webdatacommons.org/401067284

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	These envelopes are a result of the dual tones which are used for creating the various call progress audio signals.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com