Definition of "mainstream" for cellular networks 2G onwards

[japlytic]

My definition of "mainstream" for network generations 2G onwards is when services are introduced on the lower frequency (<1 GHz) bands after services are introduced on the higher frequency (>1 GHz) bands - 2G immediately became mainstream in many countries (with North America being one of the exceptions) when GSM networks started operating, and Singapore was a country which did not make 3G mainstream.
Typically, it takes 3 to 4 years for a network generation 2G onwards to become mainstream; North America was particularly slow to make 2G mainstream, and Australia made UMTS 3G mainstream about a year after services were introduced by Telstra.