diff --git a/README.md b/README.md
index ab59066..c36a7fb 100644
--- a/README.md
+++ b/README.md
@@ -96,6 +96,21 @@ The __callattendant__ uses the following hardware:
 - A 56K V.92 Data + Fax modem compatible with the **U.S. Robotics USR5637** or any device using a **Conexant CX930xx** modem have been proven effective.
 - [Optional] A GPIO based indicator board or an MQTT server.
 
+**Note:** Dell Conexant modems such as RD02-D400 are not compatible with the __callattendant__ without a firmware patch.
+A patch may be applied by adding a modem init string in the config file OPTIONAL_MODEM_INIT.
+Multiple commands may be specified by separating them with a semicolon. For example: `AT!4886=00;AT!4892=FF`
+
+ref: https://en.wikipedia.org/wiki/Network_Caller_ID (Note G)
+```
+CallerID can be reenabled in any CX93001-based modem by one of the following:
+AT!4886=00 for Bell FSK countries
+AT!4886=01 for V23 FSK (Japan)
+AT!4886=02 for ETSI FSK (France, Italy, Spain)
+AT!4886=03 for SIN227 (UK)
+AT!4886=05 for ETSI DTMF
+Sometimes additionally AT!4892=FF may be required.`
+```
+
 ---
 
 ## Software setup
diff --git a/callattendant/app.cfg.example b/callattendant/app.cfg.example
index 48efe63..16357c2 100644
--- a/callattendant/app.cfg.example
+++ b/callattendant/app.cfg.example
@@ -20,6 +20,12 @@ DEBUG = False
 # TESTING: If True function tests are executed in lieu of normal operation
 TESTING = False
 
+# Optional modem initialization string: (AT commands) to be sent to the modem
+#   Additional modem options can be set when necessary.
+#   See README.md notes regarding caller-id enable for Dell RD02-D400 modems.
+
+OPTIONAL_MODEM_INIT = ""
+
 # Web UI options: HOST can be set to a specific IP address or "::" to include IPv6
 HOST = "0.0.0.0"
 PORT = 5000
diff --git a/callattendant/config.py b/callattendant/config.py
index 138b838..5e12a5a 100644
--- a/callattendant/config.py
+++ b/callattendant/config.py
@@ -19,7 +19,7 @@
 # and screened callers through to the home phone.
 #
 default_config = {
-    "VERSION": '1.6.2',
+    "VERSION": '1.6.3',
 
     "ENV": 'production',
     "DEBUG": False,
@@ -28,6 +28,8 @@
     "HOST": "0.0.0.0",
     "PORT": 5000,
 
+    "OPTIONAL_MODEM_INIT": "",
+
     "DATABASE": "callattendant.db",
     "NOTIFICATIONS_FOLDER": "notifications",
     "SCREENING_MODE": ("whitelist", "blacklist"),
diff --git a/callattendant/hardware/modem.py b/callattendant/hardware/modem.py
index 5a059ad..e529a01 100644
--- a/callattendant/hardware/modem.py
+++ b/callattendant/hardware/modem.py
@@ -59,6 +59,8 @@
 RESET_PROFILE = "ATZ0"
 GET_MODEM_PRODUCT_CODE = "ATI0"
 GET_MODEM_SETTINGS = "AT&V"
+GET_MODEM_FIRMWARE_ID = "ATI3"
+GET_MODEM_PATCH_LEVEL_CONEXANT = "AT-PV"
 DISABLE_ECHO_COMMANDS = "ATE0"
 ENABLE_ECHO_COMMANDS = "ATE1"
 ENABLE_FORMATTED_CID = "AT+VCID=1"
@@ -585,7 +587,7 @@ def record_audio(self, audio_file_name, detect_silence=True):
                 success = False
             finally:
                 # Clear input buffer before sending commands else its
-                # contents may interpreted as the cmd's return code
+                # contents may be interpreted as the cmd's return code
                 self._serial.reset_input_buffer()
 
                 # Send End of Recieve Data state by passing "<DLE>!"
@@ -859,12 +861,13 @@ def _detect_modem(self):
         (success, result) = self._send_and_read(GET_MODEM_PRODUCT_CODE)
 
         if success:
+            # Query firmware ID
+            self._send_and_read(GET_MODEM_FIRMWARE_ID)
             if USR_5637_PRODUCT_CODE in result:
-                print("******* US Robotics Model 5637 detected **********")
+                print("*** US Robotics modem detected ***")
                 self.model = "USR"
 
             elif CONEXANT_PROODUCT_CODE in result:
-                print("******* Conextant-based modem detected **********")
                 self.model = "CONEXANT"
                 # Define the settings for the Zoom3905 where they differ from the USR5637
                 SET_VOICE_COMPRESSION = SET_VOICE_COMPRESSION_CONEXANT
@@ -872,6 +875,9 @@ def _detect_modem(self):
                 ENABLE_SILENCE_DETECTION_5_SECS = ENABLE_SILENCE_DETECTION_5_SECS_CONEXANT
                 ENABLE_SILENCE_DETECTION_10_SECS = ENABLE_SILENCE_DETECTION_10_SECS_CONEXANT
                 ENABLE_FORMATTED_CID = ENABLE_FORMATTED_CID_CONEXANT
+                # Query firmware patch level
+                self._send_and_read(GET_MODEM_PATCH_LEVEL_CONEXANT)
+                print("*** Conextant modem detected ***")
             else:
                 print("******* Unknown modem detected **********")
                 # We'll try to use the modem with the predefined USR AT commands if it supports VOICE mode.
@@ -896,6 +902,8 @@ def _init_modem(self):
         try:
             if not self._send(RESET):
                 print("Error: Unable reset to factory default")
+            if self.config["OPTIONAL_MODEM_INIT"]:
+                self._send(self.config["OPTIONAL_MODEM_INIT"])
             if not self._send(ENABLE_VERBOSE_CODES):
                 print("Error: Unable set response in verbose form")
             if not self._send(DISABLE_ECHO_COMMANDS):
diff --git a/setup.py b/setup.py
index 8a28b98..4ba680a 100644
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@
 
 setuptools.setup(
     name="callattendant",   # Add user name when uploading to TestPyPI
-    version="1.6.2",        # Ensure this is in-sync with VERSION in config.py
+    version="1.6.3",        # Ensure this is in-sync with VERSION in config.py
     author="Ted Hess",
     author_email="thess@kitschensync.net",
     description="An automated call attendant and call blocker using a USR5637 or CX930xx modem",