If you ever need to change your MGCP or h.323 cisco ATA - 186 to SIP to able to use it with Asterisk, follow this steps.
First be sure you have your ATA connected to the Internet and you have no firewalls in your connection.
Hang up the phone and press the button you will hear “Configuration menu…”
1 0 0 #
and wait for up to 5 minutes until you hear “upgrade successful” do not disconnect your ATA from the Internet nor power if off, until you hear either, “upgrade successful” or “upgrade fail”