Singapore-based Asian voice-over-internet protocol (VoIP) service provider MediaRing, has begun a cash tender offer to buy all the shares of Pacific Internet Ltd (PacNet), also based in Singapore, for USD8.25 per share. MediaRing currently owns 651,572 shares, worth 4.8% of the company, and says its offer for the communications service provider is open until 12 June. MediaRing first announced its offer to buy PacNet in February.