JOINT FILING AGREEMENT
Exhibit
A
The undersigned hereby consent to the
joint filing by any of them of a Statement on Schedule 13D and any amendments
thereto, whether heretofore or hereafter filed, relating to the securities of
iBasis, Inc., and hereby affirm that this Schedule 13D is being filed on behalf
of each of the undersigned.
Dated:
July 13, 2009
| KONINKLIJKE KPN N.V., | ||||
|
|
By:
|
/s/ Xxxx Xxxxxxx | ||
| Name: | Xxxx Xxxxxxx | |||
| Title: | Executive Vice President Finance & Attorney-in-Fact | |||
| KPN B.V., | ||||
| by: KONINKLIJKE KPN N.V., | ||||
| its sole director | ||||
| by | ||||
|
|
|
/s/ Xxxx Xxxxxxx | ||
| Name: | Xxxx Xxxxxxx | |||
| Title: | Executive Vice President Finance & Attorney-in-Fact | |||
| CELTIC ICS INC., | ||||
| by | ||||
|
|
|
/s/ Xxxx Xxxxxxx | ||
| Name: | Xxxx Xxxxxxx | |||
| Title: | President | |||
