We spoke to another expert who works in the telecom field to find out why most European networks were not experiencing the problems that AT&T and O2 did. He told Ars that Europe embraced heavy text messaging and data use far earlier than users in the US. SMS and MMS messages rely heavily on signalling channels to operate, and so networks were generally configured to dynamically manage changes in signalling traffic.
The full article can be found at Ars Technica.