Yes Sprint will pay your ETF and you can still keep your number!
I am only pushing my 40.00 because I proof of payment. Every time I seem to call they give me the run around.
I don't like to think that a person way older than me would have probably paid this, why because att said so. OH WELL! They need to be audited, I figured out more than 10 customers in February 2015 had the same issue with payment, payment arrangement, or other billing mistakes.