An unspecified number of subscribers on the Vodafone UK network were left without service on Friday after the mobile operator suffered an outage.

A customer service representative said that one of the operator’s Home Location Registers (HLR) had fallen over and could take up to 24 hours to fix, meaning customers could be without service until Saturday morning.

The HLR, one of the more arcane parts of the mobile network, is a central database for details of each mobile phone subscriber on the core network.

A Vodafone spokeswoman confirmed to telecoms.com that the network was suffering problems but could not give any further details. It is not clear how many users have been affected but Vodafone will have multiple HLRs, each serving a number of customers.

Big Red suffered a similar outage in December when it rolled out an upgrade to its SMS software, which affected the performance of its HLRs. On that occasion at least 50,000 users were affected.

Update: As of 16:50 on Friday the problem has been resolved.