This is an interesting question, particularly when it comes to understanding “IP-changing” services.
Before I answer your questions, I need to clear up some terminology that you’re using… just to be sure that we’re talking about the same thing.
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ISP versus IP
In your question, you say that you’re “using an ISP-changer program.” I think you mean an IP-hiding service or proxy.
Your ISP assigns the IP address to you. When you use an IP “changing” program, you’re not changing your ISP at all – they still provide your internet connection. In fact, you’re not really changing your IP address either, as you’re still connected to the internet using the IP address that your ISP assigned you.
The only thing that changes is the IP address that you appear to be at as seen at the other end of the connections you make.
I know it sounds like I’m being picky, but when we talk about things like security, we have to use the terminology to make sure that we’re talking about the same thing.
Once the ISP assigns the IP address to you, you can’t change your IP address. The address may change at random because it’s a dynamic IP address, but no matter what IP address it is, it will be one that your ISP gave you.
What the ISP sees
If you’re concerned about what the services you connect to can see, you can use a service (like you’re doing) that masks your IP address. These are called proxies, tunnels, or virtual private networks, depending on the specific technique that they use. (“IP changing service” is actually a rarely used, and inaccurate phrase.)
When you select one of these, your IP address doesn’t change, but you appear as if you’re coming through the IP address used by that service, not your own. All of your communications then route through that service.
Now, what your local ISP can see depends on what you’re doing and which technique you’re using.
First, they can always tell that you’re connecting to one of these proxying or anonymization services.
If it’s a simple proxy, they may be able to see what you’re transmitting.
If you’re using an encrypted VPN, then they would only see that you’re using a VPN and not the contents of the transferred data. Still, they would see the amount that’s being transferred because they are still the ones that provide you your connection to the internet and transmit to your computer all the data involved.
Like I said, it’s important to use the right terminology when you’re talking about anonymization. Whether you’re trying to hide from aggressive government enforcement or just view a video that’s blocked in your country, the needs and requirements for anonymization depend on you knowing the difference. Once you understand that, you should be able to set things up just fine.