OTE, the Hellenic Telecommunications Organisation, said in a statement that the issue had an annual coupon of 7.25 percent and was oversubscribed 3.6 times with a demand of over 1.8 billion euros.
"The company has garnered 500 million euros through the sale," an OTE spokesperson told AFP.
BNP Paribas, HSBC Bank and Morgan Stanley acted as joint bookrunners along with Greece's Alpha Bank and EFG Eurobank, the company said.
"The positive response from a wide range of bond investors, both from across Europe and further afield has been really encouraging," the group's chief financial officer Kevin Copp said in a note.
"This was a very important transaction for OTE as we begin the refinancing of 2012 maturities and build on our recent success in negotiating a new 900-million-euro bank facility," he said.
OTE said the bond was the first new benchmark issue to be issued by a Greek corporate in the past 17 months and came after its credit ratings were dropped to Baa3 by Moody's and BB by Standard and Poor's.
The Greek state, whose own debt standing has been mercilessly slashed by ratings agencies in recent months after an EU-IMF bailout averted bankruptcy, has so far issued only three and six-month treasury bills.
A planned market foray with longer-term debt has been repeatedly postponed in the face of untenable interest rates for a government which currently depends on loan instalments from the EU and the IMF to meet its obligations.
OTE in February announced cost cuts worth some 32 million euros after reporting a crushing fall in profits.
The telecom giant, where the Greek state retains a 20% stake and Deutsche Telekom has a 30% stake, had earlier said its net profits in 2010 had collapsed by 90.4 percent to 39.6 million euros.
OTE is the largest telecom operator in the Balkans employing some 30,000 people in Albania, Bulgaria, Romania and Serbia.