Frog Mobile Telephony In Greece, is a prepaid mobile telephony. With Frog you can make calls to all of Greece with a network covering over 99.6%. With Frog prepaid mobile you can roam while abroad with no previous activation procedures and no credit card deposits. Frog has 5 and 3 euros card at all kiosks. You can use all Frog services for 6 months from its initial activation. If your balance runs out before, you can continue to receive calls and short messages until the 6-month period expires. You can top up your talk time at any time by calling 1298 and following the pre-recorded instructions.