With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Rashida Jones was a cast member of The Social Network.
text_B: Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location .. phones. mobile phone. move around freely. roaming. fixed. landline. Mobile phones connect to a terrestrial cellular network of base stations -LRB- cell sites -RRB- , whereas satellite phones connect to orbiting satellites .. phones. mobile phone. cellular network. cellular network. satellite. satellite. Both networks are interconnected to the public switched telephone network -LRB- PSTN -RRB- to allow any phone in the world to be dialed .. public switched telephone network. public switched telephone network. PSTN. PSTN. In 2010 there were estimated to be five billion mobile cellular subscriptions in the world .. five billion mobile cellular subscriptions in the world. List of countries by number of mobile phones in use
not_related.