Vodafone lost its UK network this morning after trying to upgrade its SMS software.

Customers of the mobile telco weren't able to make calls between about seven and nine am this morning. An unspecified number of customers where affected, Vodafone told us, but it wasn't a peak time of day.

Another 50,000 customers weren't able to use the network until just after midday when the last of the problems where ironed out of the system. Their inconvenience was the consequence of persistent problems at one of Vodafone's home location registers (HLRs - the hubs of its network that route calls and perform other related black arts).

All of Vodafone's HLRs (an number Vodafone was not keen to discuss) were knocked out by the gremlin this morning. Vodafone's engineers couldn't isolate the problem to any single part of its network and couldn't be certain that every single customer would have been cut off - only that it was a problem that appeared to have clogged most, if not all, of its HLRs.

Vodafone's upgrade was an attempt to improve the way it stored and shared text messages across its network. It was quite an important one, by all accounts, at least as an efficiency improvement. We are led to believe they have abandoned the attempt for now.®