This integrated modem hot plug module is to be directly connected to the ADSL/Phone splitter box – an external ADSL modem is no longer required. As the router is able to directly control the chipset of the integrated modem, it is able to achieve optimized performance – even fully utilized lines stay low in latency, suitable for VoIP applications. This modem module supports ADSL with Annex-A speeds of up to 25 Mbit/s in the downstream direction. Annex B is usually only used in countries where Euro ISDN is available. Analog phone lines (POTS) usually use Annex A instead.