Quite often is mistakened for phone "sex" but in actuality, it is just simply conversing on the telephone. However, it is more appropiately used with the opposite sex. boyfriend/girlfriend type of deal, or vice versa.
"Me and my girl were phone banging until midnight before she got sleepy and went to bed."
A phrase that an asshole of a teacher uses when they catch a student texting with their phone hiding in their bag. This said teacher can normally be found teaching Chemistry.
Mr. Halliday took away my phone because he caught me “phone-bagging”
I only phone-bag because all the teacher does is talk about how we should drop out