Cell phones are used to signal presence and status:
As soon as people sit down they place their cell phone on the table in front of them. Perhaps it is possible to read too much into this action, as one townsperson explained this practice saying that it isn't comfortable to sit down with a phone in your pocket, but this action also appears symbolic and reflective of the place of phones in social life. It indicates that phones, unlike many other objects, are carried close to the body and is also practiced by women who otherwise carry phones in their bags.
By having your phone in front of you, you can access it immediately if it rings and glance at it as a new message pops up to assess its importance. Having your phone on the table is also symbolic of your intention to stay in that place for a longer period (as is accepting the offer of a cup of tea).
Cell phones are also a symbol of status, they are relatively frequently updated by those who can afford to, and once a phone is laid on the table comments are frequently made about the phone and its functionality. The layout of seating and objects on the table, even at a relaxed occasion, are complex social performances in China. Places are taken or assigned based on ideas of hierarchy and importance and offering and filling up endless cups of tea is an important task for the host or the host's wife, grandmother or older children. The introduction of cell phones as objects and intrusions into this field of play is a new addition to these social performances.