USSD: add special 'idle' handler to IUSE for testing
Change-Id: I0d566a60e95ce2da951f22ad47c6155c5b6a338c
diff --git a/doc/manuals/chapters/ussd.adoc b/doc/manuals/chapters/ussd.adoc
index 3ab587f..6100c93 100644
--- a/doc/manuals/chapters/ussd.adoc
+++ b/doc/manuals/chapters/ussd.adoc
@@ -67,7 +67,9 @@
can be assigned to one or more USSD request prefixes:
* `own-msisdn` returns subscriber's MSISDN (if assigned);
-* `own-imsi` returns subscriber's IMSI.
+* `own-imsi` returns subscriber's IMSI;
+* `test-idle` keeps the session idle until the MS terminates it, or
+ the guard timer expires (may be useful for testing).
Additional handlers can be added on request.