The application relates to idle mode mobility procedures in a femto architecture wherein a plurality of small cells constitute a preconfigured cluster of small cells. The idle mode mobility procedure comprises HNBAP messaging for UE registering and NAS messaging for location updating procedures. The small size of the cells and the corresponding higher mobility can lead to more frequent HNBAP and NAS signalling procedures. Therefore the application proposes a mechanism whereby the core network location update procedure is supplemented by a local, i.e. femto-cell-based location update procedure (630, 640), which has potentially a higher frequency than the core network location update procedure. The HNB-gateway forward location update requests from the UE only then to the core network when the core network periodic timer has been expired, the UE moves to the femtocell or the MS was turned on (606, 616, 618).