diff --git a/docs/ptt-voip-relay.txt b/docs/ptt-voip-relay.txt
index 87b9d99..ecfc652 100644
--- a/docs/ptt-voip-relay.txt
+++ b/docs/ptt-voip-relay.txt
@@ -1,12 +1,20 @@
 PTT Radio - VoIP relay
 ----------------------
 
 Using va-recorder and sip-audio-session or sip-session scripts one can relay
 audio between a PTT radio and Voice over IP using SIP Protocol.
 
 A typical usage scenario would be two PTT radios in different geographical
-locations being bridged using VoIP over IP.
+locations being bridged using VoIP over IP.  For example, by using the
+general purpose IO board provided by Raspberry Pi computer, one can control
+the PTT button of an external Radio device or detect when the radio has been
+paged from remote.  This software in this package completes the puzzle.
 
-The general purpose IO board provided by Raspberry Pi computer can control
-the PTT button of the Radio or detect when the radio has been paged from
-remote.  This software in this package completes the puzzle.
+To execute external scripts wheil handling audio calls, create inside the
+folder ~/.sipclient/scripts/ scripts with the following name patterns:
+
+ - alice@example.com-incoming-start
+ - alice@example.com-incoming-end
+ - alice@example.com-outgoing-end
+ - alice@example.com-outgoing-start
+ - alice@example.com-outgoing-fail