&gt; &gt; Something I think could be useful, and would allow a lot of<br />&gt; &gt; interoperability, would be to have a common HLR/VLR replacement.<br />&gt; &gt; The Asterisk SIP registry doesn&#39;t meet our long-term requirements<br />&gt; &gt; and so we need to develop one anyway.  If we can agree on an<br />&gt; &gt; interface and an implementation, we could do something here.<br />&gt; <br />&gt; I think I would actually want to have a protocol-compatible HLR, i.e. using the<br />&gt; standard interfaces that GSM/3GPP use for the HLR - which I doubt is something<br />&gt; that you would want to see :)<br /><br />After having a quick look at the specs :<br /> - The VLR would stay in each OpenBTS/OpenBSC instance (since it&#39;s usually attached 1:1 to a MSC)<br /> - The common part needed would group HLR/AuC/EIR<br /><br />If you want &#39;official&#39; interfaces, that means D interface, F interface & G interface to implement. Each run over SCCP and there are standardized ways to transport SCCP over IP.<br />Most of it seems to be in GSM 09.02 (using ASN.1 notation, enjoy ...) AFAICS.<br /><br />The whole VLR & D/F/G MSC side code can obviously be shared by both project and just expose an very simple internal API.<br /><br /><br />    Sylvain