Table of Contents
Supplement to Offer To Purchase For Cash
All Outstanding Shares of Common Stock
at an Increased Price of
$3.00 NET PER SHARE
a wholly owned subsidiary of
KONINKLIJKE KPN N.V.
On November 23, 2009, KPN B.V., a private limited liability company organized under the
laws of The Netherlands (“Purchaser”), which is a wholly owned subsidiary of Koninklijke KPN
N.V., a public company incorporated under the laws of The Netherlands (“Parent”), Parent, Celtic
ICS Inc., a Delaware corporation (“Merger Sub”), and iBasis, Inc., a Delaware corporation (the
“Company”), entered into a Settlement Agreement (the “Settlement Agreement”). As set forth in
this Supplement, pursuant to the Settlement Agreement, Purchaser’s offer to purchase all
outstanding shares of the Company’s common stock, par value $0.001 per share (the “Shares”),
not owned by Purchaser has been amended and supplemented as set forth herein, including as
THE OFFER (AS AMENDED) AND WITHDRAWAL RIGHTS WILL EXPIRE
AT 12:00 MIDNIGHT, NEW YORK CITY TIME, ON TUESDAY, DECEMBER 8,
2009, UNLESS THE OFFER IS FURTHER EXTENDED.
• Increased Price. The price to be paid for Shares purchased pursuant to the Offer (as
defined below) has been increased to $3.00 per Share, net to the seller in cash, without
interest and less applicable withholding taxes, upon the terms and subject to the conditions set
forth in the Offer. All Shares tendered and purchased pursuant to the Offer (including any
Shares previously validly tendered and not withdrawn) will receive the increased price.
• Extended Expiration Date. The expiration date of the Offer has been extended until
midnight, New York City time, on Tuesday, December 8, 2009 (which is the end of the day
on December 8, 2009), unless further extended.
• Majority of Minority Condition and 90% Condition. The Offer is conditioned upon,
among other things, there being valid