Why is it sometimes i cant register to a site and says my I.P is already used?

based on my experience, this happen on CDMA connection user who all of user is have the same IP, or called static IP. then, I will ask you, what connection do you use? ADSL?CDMA?GSM? or what?

This problem is very common, and frequent on those USB portable broadband modems. The root is your provider. Some providers give each client a unique IP, which will not have this problem, but others will share IPs among some users. That means, your modem will not connect to internet directly, but rather will connect to an intermediate place (the proxy server) which in turn it connects to internet and gives the webpage. The problem is that, as the only real connection to the internet is the proxy, all users have the same external IP address, that is, web sites sees as if all where using the same IP, and they don't have any way of figuring out if all those are from the same house or from a shared IP. You may try to reset your modem, unplug it and plug it again, but you'll face the exact same problem if you have one of those providers, unless you're lucky to not to be sharing IP with someone else using the same site. The only real and definitive solution to the problem is to change your ISP, and specifically look for one that gives you a non-shared unique IP, dynamic or static.

Most of the answer given here might be the answer or someone who is tech savvy that knows a lot especially the ones who do link building have scrape your IP to use for sign ups in websites or forums where they can put their website link.

The Isp provider provides 2 kinds of connection.. 1. dynamic ip address connection 2. static Ip address per connection.. your broadband service must be having a dynamic IP connecion.. where every time you switch on you computer and connect to internet your PC is assign a new IP address by your ISP.. in such case.. if some one in your neighbor also has a dynamic IP connection he may have been assigned the same IP but after he disconnects you got that IP address.. so if that user has register to a site. you may not be able to do so.. If you want to change the Ip address.. the easiest way is to switch off your router or Modem and switch it on back then it will be assigned a new IP for you to use.

try to disconnecting your internet connection for a few second, refresh it(F5 on dekstop),then connecting it again. By doing this maybe you'll get IP that haven't been used by someone else that time. Sometimes this work for me, however for a site that already had a huge amount of members it will be hard.

its because that your Internet service provider(ISP) may be giving yu an static Connection.and the same I.p may be already used by someone who joined that site u were unable to signup now.so its always a problem such way.I lve dynamic I.P's as like in my country.I enjoy more advantage even from file sharing servies such way .. there will be no limit for file downloads.ne limit is achieve just discnnect and recnnet you are on new i.p :) Happy Mylotting :D

this means that a accounts as been created using your ip address. if your internet provider gives dynamic ip address then your ip address changes every time you log in. there is a change that others can be assign with the same ip address as that of you. you can't do any thing you need to change your ip address.

I think this problem occurs when you used internet on a shared network. But as you said you are using you USB braodband connection, it also happened to me, I think the best way is to disconnect and then reconnect after some time, this ll change your IP and you ll be give with a new IP address. And if the problem persists then contact the service provider to give you your own IP address, which only belongs to you, I think this ll solve the problem Have a good day....