Abstract: A terrestrial trunked radio gateway includes a conference server configured to perform switching of audio input from a voice over internet protocol (VoIP) phone. The terrestrial trunked radio gateway further includes a pulse code modulation (PCM) driver that inserts an algebraic codebook excited linear prediction (ACELP) voice data for transmission to tetra network. A user agent server (UAS) or a user agent client (UAC) connects to the VoIP phone via a VoIP network. An access net gateway (AGW) functions as an access net common application programming interface (ACAPI) client communicating with an access net common application programming interface (ACAPI) server. The terrestrial trunked radio gateway works as a signaling gateway and allow communication between the VoIP phone and a mobile radio terminal. The VoIP phone uses a built-in algebraic codebook excited linear prediction (ACELP) codec to convert voice captured into the ACELP formulated data before transferring to tetra gateway.

Abstract: An automatic level control system for providing stabilized voice output in a radio is provided herein. The automatic level control system includes a push to talk detect section configured to detect pressing of a push to talk input section by a user. The automatic level control system further includes a level detector section configured to detect a present ‘gain’ of the automatic level control system. The automatic level control system further includes a gain decision section configured to determine a ‘gain’, based on the gain detected by the level detector section, and pressing detected by the push to talk detect section. The automatic level control system further includes a gain control section configured to receive voice input from the user through a voice input section and gain parameter from the gain decision section, and provide a stabilized voice output through the voice output section.

Abstract: A terrestrial trunked radio gateway includes a conference server configured to perform switching of audio input from a voice over internet protocol (VoIP) phone. The terrestrial trunked radio gateway further includes a pulse code modulation (PCM) driver that inserts an algebraic codebook excited linear prediction (ACELP) voice data for transmission to tetra network. A user agent server (UAS) or a user agent client (UAC) connects to the VoIP phone via a VoIP network. An an access net gateway (AGW) functions as an access net common application programming interface (ACAPI) client communicating with an access net common application programming interface (ACAPI) server. The terrestrial trunked radio gateway works as a signaling gateway and allow communication between the VoIP phone and a mobile radio terminal. The VoIP phone uses a built-in algebraic codebook excited linear prediction (ACELP) codec to convert voice captured into the ACELP formulated data before transferring to tetra gateway.