# Overview. uSipServer is a SIP "server" on Android. Simple to use. Works as SIP proxy and registrar. Supports only UDP-SIP. NOT contains VOIP3G/LTE call gateway function. # Quick Start Guide. Ex) use with CSipSimple as dial number "9999". configure properties below. Domain: SIP server domain. Default value is local IP. Local IP: listening address to SIP message.