diff --git a/platform/drivers/baseband/HR_C6000.cpp b/platform/drivers/baseband/HR_C6000.cpp
index 795e0719..fa22a7ad 100644
--- a/platform/drivers/baseband/HR_C6000.cpp
+++ b/platform/drivers/baseband/HR_C6000.cpp
@@ -67,3 +67,25 @@ void HR_C6000::setRxCtcss(const tone_t tone)
     writeCfgRegister(0xD2, 0xD0);
     writeCfgRegister(0xD4, index);        // Tone index
 }
+
+void HR_C6000::sendTone(const uint32_t freq, const uint8_t deviation)
+{
+    uint32_t tone = (freq * 65536) / 32000;
+
+    // Set  DTMF tone osc 1 to frequency of the required tone
+    writeReg16(C6000_SpiOpModes::CONFIG, 0x11A, (tone & 0xFF));
+    writeReg16(C6000_SpiOpModes::CONFIG, 0x11B, (tone >> 8) & 0xFF);
+
+    // Set  DTMF tone osc 2 to frequency of the required tone
+    writeReg16(C6000_SpiOpModes::CONFIG, 0x122, (tone & 0xFF));
+    writeReg16(C6000_SpiOpModes::CONFIG, 0x123, (tone >> 8) & 0xFF);
+
+    writeCfgRegister(0xA1, 0x02);         // Enable DTMF
+    writeCfgRegister(0xA0, deviation);    // Set DTMF tone deviation
+    writeCfgRegister(0xA4, 0xFF);         // Set the tone time to maximum
+    writeCfgRegister(0xA3, 0x00);         // Set the tone gap to zero
+    writeCfgRegister(0xD1, 0x06);         // Set the number of codes to six
+    writeCfgRegister(0xAF, 0x11);         // Set the same code to be sent six times (2 codes per register)
+    writeCfgRegister(0xAE, 0x11);
+    writeCfgRegister(0xAD, 0x11);
+}
diff --git a/platform/drivers/baseband/HR_C6000.h b/platform/drivers/baseband/HR_C6000.h
index 943b0038..8e9e4a4d 100644
--- a/platform/drivers/baseband/HR_C6000.h
+++ b/platform/drivers/baseband/HR_C6000.h
@@ -81,6 +81,36 @@ public:
     {
         writeCfgRegister(0xA1, 0x00);     // Disable all tones
     }
+
+    /**
+     * Transmit a tone of a given frequency.
+     *
+     * @param freq: tone frequency in Hz.
+     * @param deviation: tone deviation.
+     */
+    void sendTone(const uint32_t freq, const uint8_t deviation);
+
+private:
+
+    /**
+     * Write a register with 16-bit address.
+     *
+     * @param opMode: "operating mode" specifier, see datasheet for details.
+     * @param addr: register address.
+     * @param value: value to be written.
+     */
+    void writeReg16(const C6000_SpiOpModes opMode, const uint16_t addr, const uint8_t value)
+    {
+        uint8_t data[4];
+
+        data[0] =  static_cast< uint8_t >(opMode) | 0x40;
+        data[2] = (addr >> 8) & 0x07;
+        data[1] = addr & 0xFF;
+        data[3] = value;
+
+        ScopedChipSelect cs(uSpi, uCs);
+        spi_send(uSpi, data, 4);
+    }
 };
 
 #endif /* HRC6000_H */
diff --git a/platform/drivers/baseband/HR_Cx000.h b/platform/drivers/baseband/HR_Cx000.h
index a5970e85..027cdc77 100644
--- a/platform/drivers/baseband/HR_Cx000.h
+++ b/platform/drivers/baseband/HR_Cx000.h
@@ -263,6 +263,8 @@ private:
         spi_send(uSpi, seq, len);
     }
 
+protected:
+
     const struct spiDevice *uSpi;
     const struct gpioPin uCs;
 };