[shshhdhs]

Ericsson generally offers managed services, and so it's likely it was their responsibility. Also, this is reflected by O2 seeking damages.

[walshemj]

It apparently only effected a new software release - so its down to Ericson in this case.

[lovemenot]

This is supported by the fact that Softbank in Japan experiened a similar network outage at the same time. They too blame Ericsson.