A fixed external antenna installed outdoors, connected via a cable to an indoor 3G/4G router, Mi-Fi device or dongle will provide excellent Wi-Fi performance indoors. In a typical 3G/4G LTE installation the router shall allow up to 32 users to simultaneously connect to the internet via a single sim card inserted into the router. When using a 3G/4G router one has the option of plugging in a normal cordless phone into the small (RJ 11) jack at the back of the router. This offers the option of making voice telephone calls via the sim card in the router, using the cordless phone, whilst using data simultaneously.
Boosting voice requires the use of a repeater which is illegal if not supplied by the service provider. Only the service provider to whom a specific frequency has been assigned by ICASA (Independent Communication Authority of South Africa) may legally own equipment that transmits on that frequency. As much as we would love to help we simply cannot. Your service provider however has access to the necessary equipment and can help in this regard.