Remove +1 stripping from numbers in modem scripts

Note prefix stripping was unreliable because any +1XX number would break things.
The advice should be to always dial with +1 / international prefixes and store
contacts in your contacts.tsv with international codes; this way we avoid any
duplicate errors since we can be assured things in mmcli always come back w/
international prefixing automatically.

scripts/modem/sxmo_modemdial.sh

@@ -25,12 +25,7 @@ dialmenu() {
 	)"
 	echo "$NUMBER" | grep "Close Menu" && kill 0
 
-	NUMBER="$(
-		echo "$NUMBER" | 
-		awk -F' ' '{print $NF}' |
-		tr -d - |
-		cut -f2
-	)"
+	NUMBER="$(echo "$NUMBER" | cut -d: -f1 tr -d '- ')"
 	echo "$NUMBER" | grep -qE '^[+0-9]+$' || fatalerr "$NUMBER is not a number"
 
 	echo "Attempting to dial: $NUMBER" >&2