The sign for cell-phone is done by tapping a "c" hand to the upper cheek (near the ear) twice.
Many people just spell "C-E-L-L" because it is so short and easy to spell.
You should check with your local Deaf regarding how "cell phone" is signed in your area.
(Actually you should always "check" with your local Deaf regarding any and every
sign -- but emerging or relatively new signs are especially important to double
CELL PHONE (version)
The slightly compressed "C" handshape tapping twice on the side of the cheek version of cell-phone started
becoming popular in 2008 and seems to be spreading and becoming more
popular as time goes on.
A student asks: "Can you explain to me the difference between the sign for
"cell phone" & the sign for "THICK" (the one done on the cheek). They look the
same to me. "
The sign THICK (when done on the cheek) uses a strong single movement, and a
strong contact that is held just slightly longer than a typical contact-hold.
The handshape for the sign "THICK" is a "claw-like" "C" shape. The sign THICK
also tends to use puffed cheeks. Also, on rare occasion I've seen the sign THICK
done with two hands (one on each cheek).
The sign CELL phone, tends to use a double movement and makes two soft contacts
(although when signed quickly as part of a sentence it can certainly be done
with a single movement). The handshape uses a slightly compressed "C" handshape
(not a claw). The modern sign "CELL-phone" uses only one hand.