When someoee unknowning raises thier voice while using thier cell phone.
Duuuude! Don't cell yell I can hear you perfectly!!
The result of a person feeling that they need to drastically raise their voice in order to be heard on their mobile phone. Offenders of cell yell are oblivious to the fact that this is not necessary, and are often an extreme nuisance to everyone around them.
We had a hard time enjoying our meal at the restaurant, due to the cell yell of the woman at the next table.