Fix example to reflect that "never" is the default value for progressinband (bug #3129)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@4622 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/sip.conf.sample

@@ -61,7 +61,7 @@ srvlookup=yes			; Enable DNS SRV lookups on outbound calls
 ;rtpholdtimeout=300		; Terminate call if 300 seconds of no RTP activity
 				; when we're on hold (must be > rtptimeout)
 ;trustrpid = no			; If Remote-Party-ID should be trusted
-;progressinband=no		; If we should generate in-band ringing always
+;progressinband=never		; If we should generate in-band ringing always
 				; use 'never' to never use in-band signalling, even in cases
 				; where some buggy devices might not render it
 ;useragent=Asterisk PBX		; Allows you to change the user agent string