Dutch telecoms group KPN confirmed its offer of $1.55 per share for iBasis shares it does not yet own after iBasis repeatedly objected to the bid on Thursday because it was inadequate.
KPN continues to believe the offer, announced last month, is fair and that iBasis would be in a better competitive position if KPN gained full control of the U.S. international wholesale telephone call carrier, KPN said in a statement.
The 'Poison Pill' that the iBasis Board purported to adopt is without precedent and in breach of the agreements with KPN and iBasis' bylaws, KPN said.
The U.S. company has lodged a court case against KPN at a Delaware court, seeking an injunction to halt KPN's offer and other unspecified relief, iBasis said on Monday.
iBasis, of which KPN owns 56 percent, repeated on Thursday KPN's offer was inadequate and that iBasis shareholders should not tender their shares.
Shares in iBasis traded down 1.9 percent at $2.10 at 1600 GMT (12 EDT).
(Reporting by Gilbert Kreijger; Editing by David Cowell)