Yeastar 4G Wireless Connection for the S-Series VoIP Phone System with SIP Trunk over 4G LTE. The 4G LTE module enables 4G mobile data on the SIM card, making 4G LTE the primary internet connection for the S-Series VoIP phone system. It provides 4G LTE network failover for business continuity. Voice over LTE ensures faster voice connections and better call quality. This solution is suitable for temporary locations, mobile offices, and places where no fixed-line broadband is available. 4G LTE network failover offers businesses an essential internet continuity option when the primary internet connection of the phone system fails. With 4G LTE failover, SIP trunks are even more resilient. When making calls over an LTE connection, you benefit from faster voice connections, HD call quality, and other advantages that VoLTE offers for businesses.