Protocols BroadNet answer

What is a VLR (Visitor Location Register)?

Last reviewed July 22, 20261 min readReviewed by BroadNet engineering

Quick answer

The VLR (Visitor Location Register) is a temporary subscriber database attached to each MSC. When a handset camps on an MSC — at home or roaming — the VLR pulls a working copy of that subscriber's profile from the HLR, so the serving network can set up calls and deliver SMS without querying the home HLR every time. It is the local cache to the HLR's system of record.

Plain-language definitionVendor-neutralReviewed July 22, 2026

The long answer

Everything worth knowing, nothing that isn't.

§01

HLR vs VLR

The HLR is the permanent home record; the VLR is the temporary copy held by whichever MSC currently serves the subscriber. For a mobile-terminated SMS, the delivering SMSC first asks the HLR where the subscriber is, then sends MT-ForwardSM to that serving MSC — whose VLR knows how to reach the handset. See /answers/what-is-hlr and /answers/what-is-msc.

§02

Where the VLR sits in SMS delivery

SendRoutingInfoForSM to the HLR returns the address of the serving MSC; the SMSC then forwards the message to that MSC, and its VLR resolves the current radio context to page the handset. The VLR is invisible to the sender but central to why cross-operator delivery works at all. See /answers/ss7-map-send-routing-info-for-sm.

BNWritten by the BroadNet engineering team·Operating carrier-grade messaging since 2003, headquartered in Dubai·Editorial standards

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