How to register IP Phone to UC520 over Internet

[gadgroupllc]

Is there a way to register Cisco IP Phones to UC520 over Internet without VPN?

We have the following:

Cisco UC520

Cisco 7940 IP Phones

Software Version: 15.1(2)T4

Device Type: UC520-8U-4FXO-K9

[paolo bevilacqua]

It is really, really recommended to not do that.

However if you want, configure the public ip as ip source under ip telephony, on the phone configure an alternate TFTP address with CME address.

[gadgroupllc]

what is the recommendation?

[paolo bevilacqua]

To use VPN.