How are payment processed when using the phone automated system?

When paying a biller by phone using the automated system. Does it go over the internet or is it over a private network. This partially biller takes pinless debit cards, credit cards and check by phone.

I recently did a phone check-by-phone payment with Discover and that thing hit the very next day.
I dont think its the same as doing it yourself over the internet however.
Although AMEX's internet payment hits the next day too.
Go luck

It can go either way. Every company has their system set up differently to access the payment networks.

Large batches of card or ACH processing typically flow over private networks across the public Internet. The days of dedicated lines between an acquirer and the payment network are basically over.

In that is the case, How is anything secure then?

I always thought when using an atm, paying in person or by phone that it never goes over the internet.

It is very secure. Traffic from any source is heavily encrypted, and larger volumes of traffic pass across a secure virtual private network (VPN) between the source and the destination.

The risk of interception and decryption is practically zero. It doesn't happen in the real world. When there is a breach, it almost always involves the compromise of a computer system with malicious software or by means of a weak password. Hackers and identity thieves are not intercepting traffic flowing across the Internet. It is of no use to them.

Not anymore. As jw said, private lines are dying out. Internet connections are much cheaper and can be just as secure with the use of a VPN tunnel.