Hi Bojan,
First you will want to determine what you are dealing with, is it:
1) a standard text input?
3) a span that is using css styling to look like an input field with a hidden input behind it?
Open the page in your browser and use dev tools to inspect the form field and see if it's one of the above or something different?
Input text is supposed to clear before entering the text anyway, so I don't think that was the issue.
I've never tried input text with a tel field so this might be the issue? but I don't expect this to be the case.
There is another option for entering text into a field with the
Press Keys, did you try that?
`Press Keys //*[@id="phoneNumber"] (555)666-7777 `
One more thing to consider, are you actually acting on the field you think you are? again using dev tools in the browser you can test the xpath by switching to the console tab and on the console type ` $x('//*[@id="phoneNumber"] ') ` and make sure that only returns 1 result, I think from memory if robot framework finds multiple results it actions on the first result.
Hopefully something here will put you on the path to finding your answer,
Dave.