What frequency accuracy specification for cellular phone hand set? How is it achieved?
There's no "Industry Standard". Each Protocol specifies an allowable frequency error. For example, according to this R&amp;S document https://www.rohde-schwarz.co.jp/events/webinar/lte_ue_rf_measurements_v122.pdf

LTE requires 0.1PPM transmit accuracy, referenced to the received frequency. It's achieved by using a TCXO in a control loop, with the received frequency used as a reference, so it does work with the base station to control the frequency. 

The Feature phone at $20 or $30 actually costs more than that, handsets in the US are subsidized by the carriers, so what you pay is a fraction of what the carrier paid.