11 Transfer of information from HLR to VLR
23.1353GPPMulticall supplementary serviceRelease 17Stage 2TS
If the provisioning state for Multicall is "Provisioned" then when the subscriber registers on a VLR the HLR shall send that VLR information about the logical state of Multicall, Nbr_User and Nbr_SB.
If the logical state of Multicall, the subscription options Nbr_SB or Nbr_User are changed while a subscriber is registered on a VLR then the HLR shall inform the VLR of the new logical state of Multicall, the new Nbr_User or the new Nbr_SB.