UPDATE: Switch to Ericsson's Centralised User Database to blame for O2 outage?

Now that O2 seems to have fixed its network following yesterday's humiliating outage, its customers can finally start talking about why things went so badly wrong and who they can blame.

Twenty-four hours on from the peak of the outrage, O2 still hasn't responded to ITProPortal's requests for comment, with the only advice outside of the usual "our engineers are dealing with the problem as a priority" shtick issued by the company being their Maurice Moss-style encouragement for users to "try switching their mobile phones off and on."

Thankfully, more information does seem to be finally emerging, albeit independent of O2. The Channel is now citing "various sources" in saying that the day-long service blackout was down to the mobile provider's shift from a traditional Home Location Register to an Ericsson-driven Centralised User Database (CUDB).

Writing for the Channel, Bill Ray explains:

"The CUDB is supposed to consolidate user records, supporting additional applications, and provide a single point of access – but on this occasion it appears that it also provided a single point of failure. With the database unavailable, mobiles and other devices were gradually booted off the network."

This 'gradual booting' process would go some way to making sense of some of the inconsistencies of yesterday's epic network fail, which saw all aspects of O2's mobile service - voice call, text, and data - go up and down like a yo-yo, and also extended to GiffGaff and Tesco Mobile customers.

As affected subscribers line up to see what kind of apology gesture O2 is going to make - if any - Ericsson has delivered a statement saying it is now working with O2 to ensure that service remains intact and to identify the cause of the fault.

ITProPortal continues to keep a close eye on the already infamous O2 network outage. Readers wanting to get a better idea of how yesterday's disruption fits into the wider picture of recent infrastructure failures should read Rawiya Kameir blog post, while our dedicated mobile phone editor Rob Kerr has sourced the best alternative network deals for the benefit of O2's livid customers.