operate within the rails with axle support through slots in the rails. In a second form, there are castor type roller supports enclosed within the protective confines of the rails. In a third form, the slotted rails capture a grooved roller, so as to prevent upward as well as downward displacement while confining the roller to rectilinear movement. In a fourth form the track opens upwardly for the roller. In each of these four embodiments there are windows for the simultaneous movement of the roller supports into and out of working position. In a fifth form, the roller supports ride on top of support rails and each bed unit is captured in working postion by retainer means.a roaming capability by identifying approved wireless carriers. Service provisioning may also activate in the handset a Preferred Roaming List (PRL), which is a list of frequencies/bands owned by each carrier in each geographical region and which may identify preferred and/or prohibited frequencies in each region as well. Service provisioning also activates an authentication code, sometimes referred to as an “A-key,” in the cellular handset. The handset uses the A-key to authenticate the handset when the subscriber attempts to access the wireless network.
The wireless network uses a home location register (HLR) to store the A-key, the phone number, the roaming capability information, and other data related to each handset that has been or is being authenticated and provisioned by the wireless network. The HLR is a permanent database