Calls dropped after 30 minutes - Asterisk

If you notice Outbound calls dropped after 30 minutes, please note that The session timer negotiation between Asterisk and SIP provider may fails sometimes.

Proceed as below:

Edit the file /etc/asterisk/sip.conf and uncomment the following lines (in red)

; * session-timers - Session-Timers feature operates in the following three modes:
; originate : Request and run session-timers always
; accept : Run session-timers only when requested by other UA
; refuse : Do not run session timers in any case
; The default mode of operation is 'accept'.
; * session-expires - Maximum session refresh interval in seconds. Defaults to 1800 secs.
; * session-minse - Minimum session refresh interval in seconds. Defualts to 90 secs.
; * session-refresher - The session refresher (uac|uas). Defaults to 'uas'.
; uac - Default to the caller initially refreshing when possible
; uas - Default to the callee initially refreshing when possible
;
; Note that, due to recommendations in RFC 4028, Asterisk will always honor the other
; endpoint's preference for who will handle refreshes. Asterisk will never override the
; preferences of the other endpoint. Doing so could result in Asterisk and the endpoint
; fighting over who sends the refreshes. This holds true for the initiation of session
; timers and subsequent re-INVITE requests whether Asterisk is the caller or callee, or
; whether Asterisk is currently the refresher or not.
;

session-timers=accept
session-expires=600

;session-minse=90
;session-refresher=uac

Restart the Asterisk service