#!/bin/sh
cnt=0
faxcnt=0
faxcnt2=0
while true
do
    for((cnt=1;cnt<6;cnt++))
    do
        faxcnt=`/usr/bin/faxstat | grep "Receiving from" -c`
        faxcnt2=$faxcnt2+$faxcnt
        echo "counter on: " $cnt
        echo "fax counter:" $faxcnt2
        sleep 5
    done
    faxcnt2=0

done

output:

counter on:  1
fax counter: 0+2
counter on:  2
fax counter: 0+2+2
counter on:  3
fax counter: 0+2+2+2
counter on:  4
fax counter: 0+2+2+2+2
counter on:  5
fax counter: 0+2+2+2+2+2