asterisk: Add missing 0-digit prefix in user

Change-Id: Ia12552cf70c4c0f2c71cd9d5b70c608c883fb170
diff --git a/asterisk/Asterisk_Tests.ttcn b/asterisk/Asterisk_Tests.ttcn
index 5d9754e..9402f0d 100644
--- a/asterisk/Asterisk_Tests.ttcn
+++ b/asterisk/Asterisk_Tests.ttcn
@@ -79,7 +79,7 @@
 }
 
 function f_init_ConnHdlrPars(integer idx := 1) runs on test_CT return ConnHdlrPars {
-	var ConnHdlrPars pars := valueof(t_Pars(int2str(500 + idx)));
+	var ConnHdlrPars pars := valueof(t_Pars("0" & int2str(500 + idx)));
 	return pars;
 }