simplify code to get phone number for incoming calls

This code uses fewer programs and the code now matches the code for
getting phone number of incoming text.

Signed-off-by: Anjandev Momi <anjan@momi.ca>
Signed-off-by: Maarten van Gompel <proycon@anaproy.nl>

scripts/modem/sxmo_modemmonitor.sh

@@ -22,9 +22,7 @@ modem_n() {
 lookupnumberfromcallid() {
 	VOICECALLID=$1
 	mmcli -m "$(modem_n)" --voice-list-calls -o "$VOICECALLID" -K |
-		grep call.properties.number |
-		cut -d ':' -f 2 |
-		tr -d ' '
+		sed -E 's/^call\.properties\.number\s+:\s+//'
 }
 
 checkformissedcalls() {