USER=1000
REALM=asterisk
PASSWORD=password
NONCE=1f0c3970
URI=sip:127.0.0.1

str1=$USER:$REALM:$PASSWORD
str2=REGISTER:$URI

hash1=`echo -n $str1 | md5sum | head -c 32`
hash2=`echo -n $str2 | md5sum | head -c 32`

echo -n $hash1:$NONCE:$hash2 | md5sum