Backup Internet and Provider Re-Registration

Configuring Backup Internet

If your PBX is behind NAT and its public IP address changes, the PBX may not receive incoming calls until it re-registers with the provider, which by default can take 2–6 minutes.

Create the IP Check Script

1. Connect using SSH into your MikoPBX (documentation about different ways to do that - here)

2. Create a new script file with this command:

cat > /storage/usbdisk1/mikopbx/custom_modules/update_ip.sh

The system will wait for input; paste the following script into the terminal:

#!/bin/bash
# File to store the previous IP
IP_FILE="/tmp/last_ip.txt"
# Command to retrieve the current public IP
CURRENT_IP=$(/usr/bin/curl -s https://checkip.amazonaws.com)

# Check if the file with the previous IP exists
if [ -f "$IP_FILE" ]; then
    LAST_IP=$(cat "$IP_FILE")
else
    LAST_IP=""
fi

# Compare the current IP with the previous IP
if [ "$CURRENT_IP" != "$LAST_IP" ]; then
    /bin/busybox logger -t 'UpdateIP' "IP changed: $LAST_IP -> $CURRENT_IP"
    echo "$CURRENT_IP" > "$IP_FILE"
    # Trigger an Asterisk command
    /usr/sbin/asterisk -rx 'pjsip send register *all'
fi

1. Press CTRL+D to finish.

2. Make the file executable:

chmod +x /storage/usbdisk1/mikopbx/custom_modules/update_ip.sh

Schedule the Script

1. Go to the MikoPBX web interface → "System" → "System file customization":

"System file customization" section

1. Open the file: /var/spool/cron/crontabs/root

"crontabs/root" file

1. Append the following line to the end of the file:

*/1 * * * * /storage/usbdisk1/mikopbx/custom_modules/update_ip.sh > /dev/null 2> /dev/null

This schedule runs the script every minute to check for a changed public IP. If the IP has changed, it re-registers all providers.

Editing file crontabs/root

If the IP changes, you’ll see an informational log in system/messages stating the old and new IP addresses.