Mobile development

I need an Android app. I would like it designed and built. on the old nokia cell phones, dial-up internet was used (formerly also on windows through 56k fax modems) I need Android to connect like this. the app should have only one screen and a button to connect the connection data will be unique and should stay in the backend the number, user and password will be unique (backend) in the only screen should have an input to type user, once connected you take this input and check on my site if the result is 1 or 0 If it is 1 keep it connected if not disconnect all connections will be with the same phone, user and password (unicos, I will provide you)