Is asking for users own phone number a bad user experience?

By bad I mean up to the point of not wanting to continue with the app and uninstalling it.

I'm developing an app which needs, well it could be better said that is essential for the app, the user to input its phone number correctly.

Applications that need that usually work with an SMS system that helps to confirm the phone number, but in my case I've checked some services that offer this service and their prices are way bigger than the money I expect to win with the app, making and maintaining my own service for this would also very likely prove way more expensive than the money I would win. And I'm not into that.

So, I'd like to have some opinions about how bad of a user experience this is. If I get that this is bad user experience I'll get to check more of those services, perhaps one of them offers free verification if there are not too many SMS per month. If I get the opinion that it's not that bad or if I don't find those services, I'd just release the app this way, as it cannot be helped.

Thanks for your attention.