пополнить счёт(one's phone) "Top up" is known in the U.S., being the terminology used by MetroPCS, Boost Mobile, NET10, and of course Virgin Mobile. The major prepaid providers, however– T-Mobile, AT&T, Verizon Wireless– all use refill. Because pre-paid mobile plans are not as prevalent in the U.S., I would always specify that it is your phone whether you are topping up, refilling, adding credit, or adding minutes." (english.stackexchange.com) • But the other common use of top-up these days is what you do to a pay-as-you-go (BrE) mobile/(AmE) cell phone. ... Which led me to wonder: what do Americans say for that? Pay-as-you-go phones are much more common in the UK than in the US, but from what I can gather from the interwebs, refill is used in this context too. Here's a 2004 news release about an American "prepay" phone service • "As always, Verizon Wireless prepay service allows customers to refill their minutes over the phone, at a Verizon Wireless Communications Store, online, as well as at RadioShack, Circuit City and other authorized agents."blogspot.com4uzhoj)