GSM roaming with the YateUCNTM
For GSM/GPRS roaming, the YateUCN uses the Camel/MAP protocol to perform roaming between the visited and the home networks.
The YateUCN performs all the functions of typical MSC/VLR/SGSN/GGSN of a GSM/GPRS core network.
The YateUCN implements the MAP protocol to ensure communication between its MSC component and the HLR from the home network, as well as with the GMSC (Gateway Mobile Switching Centre).
For GPRS, the YateUCN uses GTP to enable connectivity between its SGSN (Serving GPRS Support Node) component and the GGSN (Gateway GPRS Support Node) from the home network; it also authenticates the subscriber by connecting to the home HLR, using the home GGSN as a gateway.
Local IP breakout can be provided from the YateUCN.
GSM roaming in conventional network
For voice calls performed in the visited network, typical GSM networks rely on location update and authentication from the home HLR.
If a roaming subscriber receives a call, since the HLR knows the VLR/visited-MSC where the MS is registered, it sends out a request to the visited MSC to assign the MSRN (Mobile Station Roaming Number) number to which the GMSC will then route the call.
The MSRN is returned to the HLR, which sends it to the GMSC, which routes the call to the v-MSC.
The MSRN contains the current visited country code and the current MSC code, so that the call can be routed accordingly to the MS.