Sonus Networks' (SONS) purchase of Network Equipment Technologies (NWK) will intensify competition in the VoIP, or voice over Internet protocol, infrastructure market, analysts say. Sonus competes in VoIP networking gear with Acme Packet (APKT), privately held Genband and others. The companies make session border controllers, or SBCs, devices that set up Internet calls over landline and wireless phone networks. Sonus on Tuesday said it has agreed