Some countries are listed twice: once as the country, and once with “(Virtual)” after the name. The plain listing is real mobile numbers, the kind a phone carries. The “(Virtual)” listing is numbers from online phone services (VoIP). Prices and stock differ between the two.
Many websites can tell the two apart and refuse the virtual kind, with a message such as “virtual phone numbers are not accepted”, because they are easy to get in bulk. If that happens, or the code never comes, buy from the plain listing of the same country. You pay only for codes that arrive, so trying costs nothing.