#!/bin/sh 
# monitor_sip.sh
# David Rowe 18 Feb 2010
# Adapted from script found on http://www.voip-info.org/wiki-IAX
#
# It was found that SIP 
# trunks we losing registration ever day or so as the ppp link IP
# changed.  The NAT router (Linux OpenWRT 2.4 box in my case) was mistakenly
# sending SIP messages with the previous PPP IP, as it was
# relying on some sort of internal hash table.  Stopping SIP messages
# for 2 minutes resets the NAT router.

cd /usr/bin 
PATH=/sbin:/bin:/usr/sbin:/usr/bin

while [ 1 ]
do
  /sbin/asterisk "-rx sip show registry" 2>/dev/null > /tmp/sipshowregistry.txt
  sleep 1

  # Test to see if our SIP trunk is up

  TEST="111720.*Registered"
  if grep $TEST /tmp/sipshowregistry.txt > /dev/null
  then
    echo "OK"
    sleep 60  # all is well...
  else
    echo "oops"
    
    # we have lost our SIP trunk, log problem and
    # restart Asterisk to get router NAT tables to reset
  
    date >> /var/log/monitor_sip.txt
   
    /etc/init.d/asterisk stop
    sleep 240
    # & hopefully stops Asterisk disconnection when this script is killed	
    /etc/init.d/asterisk start
    
    # give Asterisk time to wake up before we test start again
    sleep 60
  fi
done