diff --git a/app/app.c b/app/app.c
index 9a44493..bac74a1 100644
--- a/app/app.c
+++ b/app/app.c
@@ -54,7 +54,7 @@
 
 static void APP_ProcessKey(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld);
 
-static void FUN_00005144(void)
+static void APP_CheckForIncoming(void)
 {
 	if (!g_SquelchLost) {
 		return;
@@ -70,33 +70,33 @@ static void FUN_00005144(void)
 				gNOAA_Countdown = 20;
 				gScheduleNOAA = false;
 			}
-			FUNCTION_Select(FUNCTION_3);
+			FUNCTION_Select(FUNCTION_INCOMING);
 			return;
 		}
 		if (gRxReceptionMode != RX_MODE_NONE) {
-			FUNCTION_Select(FUNCTION_3);
+			FUNCTION_Select(FUNCTION_INCOMING);
 			return;
 		}
 		gDualWatchCountdown = 100;
 		gScheduleDualWatch = false;
 	} else {
 		if (gRxReceptionMode != RX_MODE_NONE) {
-			FUNCTION_Select(FUNCTION_3);
+			FUNCTION_Select(FUNCTION_INCOMING);
 			return;
 		}
 		ScanPauseDelayIn10msec = 20;
 		gScheduleScanListen = false;
 	}
 	gRxReceptionMode = RX_MODE_DETECTED;
-	FUNCTION_Select(FUNCTION_3);
+	FUNCTION_Select(FUNCTION_INCOMING);
 }
 
-void FUN_000051e8(void)
+static void APP_HandleIncoming(void)
 {
 	bool bFlag;
 
 	if (!g_SquelchLost) {
-		FUNCTION_Select(FUNCTION_0);
+		FUNCTION_Select(FUNCTION_FOREGROUND);
 		gUpdateDisplay = true;
 		return;
 	}
@@ -294,16 +294,16 @@ Skip:
 void FUN_0000510c(void)
 {
 	switch (gCurrentFunction) {
-	case FUNCTION_0:
-		FUN_00005144();
+	case FUNCTION_FOREGROUND:
+		APP_CheckForIncoming();
 		break;
 	case FUNCTION_POWER_SAVE:
 		if (!gRxIdleMode) {
-			FUN_00005144();
+			APP_CheckForIncoming();
 		}
 		break;
-	case FUNCTION_3:
-		FUN_000051e8();
+	case FUNCTION_INCOMING:
+		APP_HandleIncoming();
 		break;
 	case FUNCTION_RECEIVE:
 		FUN_000052f0();
@@ -463,7 +463,7 @@ Skip:
 	}
 }
 
-void NOAA_IncreaseChannel(void)
+static void NOAA_IncreaseChannel(void)
 {
 	gNoaaChannel++;
 	if (gNoaaChannel > 9) {
@@ -581,7 +581,7 @@ void APP_EndTransmission(void)
 	RADIO_SetupRegisters(false);
 }
 
-static void FUN_00008334(void)
+static void APP_HandleVox(void)
 {
 	if (!gSetting_KILLED) {
 		if (g_200003B6 == 0) {
@@ -601,11 +601,11 @@ static void FUN_00008334(void)
 				}
 				if (gCurrentFunction == FUNCTION_TRANSMIT && !gPttIsPressed && !gVOX_NoiseDetected) {
 					if (gFlagEndTransmission) {
-						FUNCTION_Select(FUNCTION_0);
+						FUNCTION_Select(FUNCTION_FOREGROUND);
 					} else {
 						APP_EndTransmission();
 						if (gEeprom.REPEATER_TAIL_TONE_ELIMINATION == 0) {
-							FUNCTION_Select(FUNCTION_0);
+							FUNCTION_Select(FUNCTION_FOREGROUND);
 						} else {
 							gRTTECountdown = gEeprom.REPEATER_TAIL_TONE_ELIMINATION * 10;
 						}
@@ -617,7 +617,7 @@ static void FUN_00008334(void)
 			} else if (g_VOX_Lost) {
 				gVOX_NoiseDetected = true;
 				if (gCurrentFunction == FUNCTION_POWER_SAVE) {
-					FUNCTION_Select(FUNCTION_0);
+					FUNCTION_Select(FUNCTION_FOREGROUND);
 				}
 				if (gCurrentFunction != FUNCTION_TRANSMIT) {
 					gDTMF_ReplyState = DTMF_REPLY_NONE;
@@ -657,13 +657,13 @@ void APP_Update(void)
 
 	if (gScreenToDisplay != DISPLAY_SCANNER && gScanState != SCAN_OFF && gScheduleScanListen && !gPttIsPressed && gVoiceWriteIndex == 0) {
 		if (IS_FREQ_CHANNEL(gNextMrChannel)) {
-			if (gCurrentFunction == FUNCTION_3) {
+			if (gCurrentFunction == FUNCTION_INCOMING) {
 				APP_StartListening(FUNCTION_RECEIVE);
 			} else {
 				FREQ_NextChannel();
 			}
 		} else {
-			if (gCopyOfCodeType == CODE_TYPE_OFF && gCurrentFunction == FUNCTION_3) {
+			if (gCopyOfCodeType == CODE_TYPE_OFF && gCurrentFunction == FUNCTION_INCOMING) {
 				APP_StartListening(FUNCTION_RECEIVE);
 			} else {
 				MR_NextChannel();
@@ -709,7 +709,7 @@ void APP_Update(void)
 	}
 
 	if (gEeprom.VOX_SWITCH) {
-		FUN_00008334();
+		APP_HandleVox();
 	}
 
 	if (gSchedulePowerSave) {
@@ -909,7 +909,7 @@ void APP_TimeSlice10ms(void)
 		if (gRTTECountdown) {
 			gRTTECountdown--;
 			if (gRTTECountdown == 0) {
-				FUNCTION_Select(FUNCTION_0);
+				FUNCTION_Select(FUNCTION_FOREGROUND);
 				gUpdateDisplay = true;
 			}
 		}
@@ -1296,7 +1296,7 @@ static void APP_ProcessKey(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 	bool bFlag;
 
 	if (gCurrentFunction == FUNCTION_POWER_SAVE) {
-		FUNCTION_Select(FUNCTION_0);
+		FUNCTION_Select(FUNCTION_FOREGROUND);
 	}
 	gBatterySaveCountdown = 1000;
 	if (gEeprom.AUTO_KEYPAD_LOCK) {
@@ -1462,7 +1462,7 @@ static void APP_ProcessKey(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 			} else if (!bKeyHeld && bKeyPressed) {
 				FUN_00001150();
 				if (gEeprom.REPEATER_TAIL_TONE_ELIMINATION == 0) {
-					FUNCTION_Select(FUNCTION_0);
+					FUNCTION_Select(FUNCTION_FOREGROUND);
 				} else {
 					gRTTECountdown = gEeprom.REPEATER_TAIL_TONE_ELIMINATION * 10;
 				}
diff --git a/app/app.h b/app/app.h
index fc42d94..e8e1979 100644
--- a/app/app.h
+++ b/app/app.h
@@ -19,11 +19,13 @@
 
 #include <stdbool.h>
 #include "functions.h"
+#include "radio.h"
 
 void FUN_0000773c(void);
 void APP_EndTransmission(void);
 void CHANNEL_Next(bool bFlag, int8_t Direction);
 void APP_StartListening(FUNCTION_Type_t Function);
+void APP_SetFrequencyByStep(VFO_Info_t *pInfo, int8_t Step);
 
 void APP_Update(void);
 void APP_TimeSlice10ms(void);
diff --git a/app/generic.c b/app/generic.c
index 6267fc1..9e7f809 100644
--- a/app/generic.c
+++ b/app/generic.c
@@ -82,11 +82,11 @@ void GENERIC_Key_PTT(bool bKeyPressed)
 		if (gScreenToDisplay == DISPLAY_MAIN) {
 			if (gCurrentFunction == FUNCTION_TRANSMIT) {
 				if (gFlagEndTransmission) {
-					FUNCTION_Select(FUNCTION_0);
+					FUNCTION_Select(FUNCTION_FOREGROUND);
 				} else {
 					APP_EndTransmission();
 					if (gEeprom.REPEATER_TAIL_TONE_ELIMINATION == 0) {
-						FUNCTION_Select(FUNCTION_0);
+						FUNCTION_Select(FUNCTION_FOREGROUND);
 					} else {
 						gRTTECountdown = gEeprom.REPEATER_TAIL_TONE_ELIMINATION * 10;
 					}
diff --git a/app/main.c b/app/main.c
index 7b8e761..c3b46e4 100644
--- a/app/main.c
+++ b/app/main.c
@@ -30,8 +30,6 @@
 #include "ui/inputbox.h"
 #include "ui/ui.h"
 
-extern void APP_SetFrequencyByStep(VFO_Info_t *pInfo, int8_t Step);
-
 static void MAIN_Key_DIGITS(KEY_Code_t Key, bool bKeyPressed, bool bKeyHeld)
 {
 	uint8_t Vfo;
diff --git a/app/uart.c b/app/uart.c
index 0364950..c78b0bd 100644
--- a/app/uart.c
+++ b/app/uart.c
@@ -369,7 +369,7 @@ static void CMD_052F(const uint8_t *pBuffer)
 	gEeprom.VfoInfo[0].DTMF_DECODING_ENABLE = false;
 	gIsNoaaMode = false;
 	if (gCurrentFunction == FUNCTION_POWER_SAVE) {
-		FUNCTION_Select(FUNCTION_0);
+		FUNCTION_Select(FUNCTION_FOREGROUND);
 	}
 	Timestamp = pCmd->Timestamp;
 	GPIO_ClearBit(&GPIOB->DATA, GPIOB_PIN_BACKLIGHT);
diff --git a/functions.c b/functions.c
index 936e0ea..0bbe1b1 100644
--- a/functions.c
+++ b/functions.c
@@ -83,7 +83,7 @@ void FUNCTION_Select(FUNCTION_Type_t Function)
 	}
 
 	switch (Function) {
-	case FUNCTION_0:
+	case FUNCTION_FOREGROUND:
 		if (gDTMF_ReplyState != DTMF_REPLY_NONE) {
 			RADIO_PrepareCssTX();
 		}
@@ -103,7 +103,7 @@ void FUNCTION_Select(FUNCTION_Type_t Function)
 		break;
 
 	case FUNCTION_MONITOR:
-	case FUNCTION_3:
+	case FUNCTION_INCOMING:
 	case FUNCTION_RECEIVE:
 		gBatterySaveCountdown = 1000;
 		gSchedulePowerSave = false;
diff --git a/functions.h b/functions.h
index e1427a2..1cc836f 100644
--- a/functions.h
+++ b/functions.h
@@ -20,11 +20,11 @@
 #include <stdint.h>
 
 enum FUNCTION_Type_t {
-	FUNCTION_0 = 0U,
-	FUNCTION_TRANSMIT = 1U,
-	FUNCTION_MONITOR = 2U,
-	FUNCTION_3 = 3U,
-	FUNCTION_RECEIVE = 4U,
+	FUNCTION_FOREGROUND = 0U,
+	FUNCTION_TRANSMIT   = 1U,
+	FUNCTION_MONITOR    = 2U,
+	FUNCTION_INCOMING   = 3U,
+	FUNCTION_RECEIVE    = 4U,
 	FUNCTION_POWER_SAVE = 5U,
 };
 
diff --git a/radio.c b/radio.c
index d758ffc..31a900f 100644
--- a/radio.c
+++ b/radio.c
@@ -602,7 +602,7 @@ void RADIO_SetupRegisters(bool bSwitchToFunction0)
 	FUNCTION_Init();
 
 	if (bSwitchToFunction0) {
-		FUNCTION_Select(FUNCTION_0);
+		FUNCTION_Select(FUNCTION_FOREGROUND);
 	}
 }
 
diff --git a/scheduler.c b/scheduler.c
index 1987087..919e38a 100644
--- a/scheduler.c
+++ b/scheduler.c
@@ -55,7 +55,7 @@ void SystickHandler(void)
 	if (gFoundCTCSSCountdown) {
 		gFoundCTCSSCountdown--;
 	}
-	if (gCurrentFunction == FUNCTION_0) {
+	if (gCurrentFunction == FUNCTION_FOREGROUND) {
 		DECREMENT_AND_TRIGGER(gBatterySaveCountdown, gSchedulePowerSave);
 	}
 	if (gCurrentFunction == FUNCTION_POWER_SAVE) {