Ok, so when a user inputs nothing, simply pressing enter when prompted for a phone number, I get a "./addrbkfct.sh: test: argument expected" error message. I have the following function:
addNumber(){
echo "Phone number: \c";
read number;
echo $number;
if [ -z $number ] ; then
echo "WARNING: no number";
addEmail "$1" "$2" "$number";
else
echo $number | egrep '[+]?[-]?[0-9]?[0-9]?[0-9]?[-]?[0-9][0-9][0-9][-]?[0-9][0-9][0-9][0-9]';
if [ $? -eq 0 ] ; then
addEmail "$1" "$2" "$number";
else
addNumber "$1" "$2";
fi
fi
}