Assertion: phone number | /r/HasAspect | format
Facets:
value: over the course of telephone history
type: TEMPORAL
Source sentences:
text: Over the course of telephone history, telephone numbers had various lengths and formats, and even included most letters of the alphabet in leading positions when telephone exchange names were in common use until the 1960s.
text: For example, the same US phone number can have all of the formats listed below: