diff --git a/voice-client/files/etc/asterisk_templates/sip.conf.TEMPLATE b/voice-client/files/etc/asterisk_templates/sip.conf.TEMPLATE
index 4446e0f8b..f9a4889e5 100644
--- a/voice-client/files/etc/asterisk_templates/sip.conf.TEMPLATE
+++ b/voice-client/files/etc/asterisk_templates/sip.conf.TEMPLATE
@@ -22,6 +22,8 @@ directmedia=no
 sipdebug=no
 session-timers=refuse
 videosupport=yes
+disallow=all
+allow=alaw
 
 realm=|REALM|
 defaultexpiry=|DEFAULTEXPIRY|