Siemens Gigaset C450 User Manual (English)

Questions and Answers:

J
juan28Jul 28, 2025
Why can't I send messages from my Siemens Gigaset C450?
- K
  Katrina RoblesJul 29, 2025
  There are several reasons why you might be unable to send messages. First, check if you have requested the CLIP service (Calling Line Identification Presentation) from your service provider, as this service might not be enabled. If the CLIP service is enabled, text message transmission might have been interrupted (e.g., by a call). In this case, try re-sending the text message. Also, make sure you have entered the phone number.
K
Kristin JimenezAug 1, 2025
What to do if the message is played back on my Siemens Gigaset C450 Telephone?
- C
  coopermorganAug 2, 2025
  The message is played back because the 'display call number' service is not activated. Ask your service provider to activate this function. It could also be that the mobile phone operator and network SMS service provider have not agreed on cooperation, so you should obtain information from your network SMS service provider. Another reason could be that your terminal is recorded in the records of your SMS provider as having no fixed network SMS functionality; in this case, register your terminal again for SMS reception.
L
larry76Aug 6, 2025
What to do if messages are only received as voice messages during the day on my Siemens Gigaset C450?
- J
  Jenny PierceAug 6, 2025
  This issue occurs when the terminal is stored in your SMS provider's database as having no fixed network SMS functionality, meaning you are no longer registered with the provider. To resolve this, register your terminal again for SMS reception.
R
Ryan AndradeAug 10, 2025
Why can't I send messages from my Siemens Cordless Telephone?
- J
  jason44Aug 10, 2025
  There can be several reasons why you can't send messages with your Siemens Cordless Telephone. First, ensure that the CLIP service (Calling Line Identification Presentation) is enabled by contacting your service provider. If SMS transmission was interrupted, try re-sending the SMS. Also, verify that your network provider supports this feature. Finally, check that the SMS centre number is correctly entered; if not, input the correct number.
D
daniel42Aug 15, 2025
What to do if I have stopped receiving SMS messages on my Siemens Cordless Telephone?
- L
  Lori VazquezAug 15, 2025
  If you have stopped receiving SMS messages on your Siemens Cordless Telephone, it might be due to a changed mailbox ID. Update your SMS contacts with your new ID or revert the change. Ensure your mailbox is activated. Also, check if call diversion is activated for All Calls, and if so, change the call diversion settings.
J
Joseph SmithAug 19, 2025
Why are messages only received during the day on my Siemens Cordless Telephone?
- T
  Tony PerezAug 20, 2025
  Messages are only received during the day on your Siemens Cordless Telephone because the terminal is recorded in your SMS provider's database as not having fixed network SMS functionality. To resolve this, obtain information from your fixed network SMS service provider or have the device re-registered to receive SMS messages.
K
Kristine SotoAug 23, 2025
What to do if I receive an incomplete SMS on my Siemens Cordless Telephone?
- B
  Brenda WhiteAug 23, 2025
  If you receive an incomplete SMS on your Siemens Cordless Telephone, it might be due to your phone's memory being full. Try deleting old SMS messages.

Siemens Gigaset C450 Specifications

General

Frequency	1.9 GHz
Display	Yes
Display Type	LCD
Standby Time	Up to 300 hours
Phonebook Capacity	50 entries
Range (Outdoors)	300 meters
Range (Indoors)	50 meters
Caller ID	Yes
Hands-free	Yes
Alarm	Yes
Eco Mode	Yes
Number of Handsets	1
Answering Machine	No
Intercom	Yes
Conference Call	Yes
Headset Jack	Yes
Power Supply (Handset)	Rechargeable battery
Type	Cordless Phone
Power Supply (Base)	AC adapter

Summary

The handset at a glance

Siemens Gigaset contact numbers

Provides contact information for customer support and repairs.

The base station at a glance

Safety precautions

General safety warnings

Important warnings regarding product use, battery handling, and environmental safety.

First steps

Pack contents

Lists all items included in the Gigaset C470/C475 package.

Installing the base station

Instructions for initial placement and setup of the base station.

Range and reception strength

Details on the operational range and signal quality between handset and base.

Connecting the base station

Step-by-step guide to connect the base station to power and telephone line.

Setting up the handset for use

Procedures for preparing the handset, including inserting batteries and closing the cover.

Attaching the belt clip

Instructions on how to attach the belt clip to the handset.

Opening the battery cover

Guide on how to open the handset's battery compartment.

Placing the handset in the base station and registering

Steps for automatically registering the handset with the base station.

Headset socket

Information about the type of headsets compatible with the device.

Initial charging and discharging of batteries

Guide for the first battery charge and discharge cycle for optimal performance.

Setting the date and time

Instructions on setting the date and time for call logging and alarm functions.

Display in idle status

Shows an example of the handset display when it is not in use.

Operating the handset

Activating/deactivating the handset

How to turn the handset on or off.

Activating/deactivating the keypad lock

Instructions to lock and unlock the handset keypad to prevent accidental use.

Control key

Explanation of the functions and navigation of the control key.

Display keys

Describes the context-sensitive functions of the display keys.

Reverting to idle status

How to return the handset to its standby screen from any menu.

Menu guidance

Explains how to navigate through the phone's menu structure to access functions.

Correcting incorrect entries

Steps for editing or deleting characters when entering data.

ECO DECT

Activating/deactivating eco mode:

How to enable or disable eco mode to reduce power consumption and transmission power.

Menu tree

Making calls

Making an external call

Guide on how to place calls to numbers outside the internal network.

Ending a call

Simple instructions on how to terminate an ongoing call.

Accepting a call

How to answer an incoming call using different methods.

Calling Line Identification

Explains the requirements and function of Caller ID (CLIP/CLI).

Call display with CLIP/CLI

How caller information is displayed on the screen, including names and pictures.

Switching between earpiece and handsfree mode

How to toggle between using the handset earpiece and the speakerphone.

Muting

Instructions on how to temporarily mute the microphone during a call.

Making calls using network services

Setting functions for the next call

How to set call-related functions for a single outgoing call.

Setting functions for all subsequent calls

How to configure call features for all future calls.

Functions during a call

Features available during an active call like call diversion and call waiting.

Functions after a call

Features available after a call, such as cancelling ringback or managing network mailbox.

Activating/deactivating the network mailbox

How to enable or disable the network mailbox service.

Using the directory and lists

Directory/call-by-call list

Information on storing and managing phone numbers and network provider prefixes.

Saving a number in the directory

Steps to save new contact details into the phone's directory.

Saving a number in the call-by-call list

How to save network provider codes for cost-effective calls.

Order of directory entries

Explains the sorting logic for entries within the phone directory.

Selecting entries in the directory and call-by-call lists

How to find and select specific entries from stored lists.

Dialling with the directory/call-by-call list

Process of making calls directly from stored directory or call-by-call entries.

Managing directory/call-by-call entries

Overview of functions for editing, deleting, and copying entries.

Viewing entries

How to display saved contact information.

Editing entries

Steps to modify existing directory or call-by-call list entries.

Using other functions

Accessing additional features like VIP marking and list management.

Using quick dial keys

How to assign and use keys for rapid access to frequently called numbers.

Sending the directory/call-by-call list to another handset

Procedure for transferring contact lists between registered handsets.

Copying a displayed number to the directory

How to save numbers directly from call history or other displays into the directory.

Copying a number from the directory

Instructions on how to copy numbers from the directory to other functions.

Last number redial list

Information about the list of recently dialled numbers.

Manual last number redial

How to redial the last number manually.

Managing entries in the last number redial list

Functions for viewing and managing numbers in the last number redial list.

Opening lists with the message key

How to access SMS, call history, and answer machine lists using the message key.

Incoming SMS message list

How received SMS messages are stored and displayed.

Call history

Details about viewing incoming and outgoing calls, including missed ones.

Setting the call history type

Options to configure how call history data is saved.

Answer machine list (Gigaset C475 only)

How to access and manage voice messages from the answer machine.

Making cost-effective calls

Linking call-by-call numbers with one number

How to associate network provider codes with specific numbers for automatic dialling.

Automatic network provider preselection (preselection)

Setting up automatic selection of call-by-call numbers based on dialed prefixes.

Saving preselection numbers

Steps to save and manage preselection numbers for cost-saving calls.

Save or change entries in the preselection lists

Managing saved numbers in the preselection lists for call routing.

Temporarily cancelling preselection

How to temporarily disable automatic preselection for calls.

Permanently deactivating preselection

Steps to remove saved preselection numbers.

SMS (text messages)

Writing/sending an SMS

Guide on composing and transmitting SMS messages.

Writing an SMS

Detailed steps for creating a new SMS message.

Sending an SMS

How to send a composed SMS message, including recipient details.

Draft message list

Managing SMS messages that have been saved but not yet sent.

Saving an SMS in the draft message list

How to save a message in the draft folder for later use.

Opening the draft message list

Accessing the saved draft SMS messages.

Reading or deleting individual SMS messages

How to view and remove specific SMS messages from lists.

Writing/changing an SMS

Editing existing SMS messages or writing new ones.

Deleting draft message list

Clearing all saved draft SMS messages.

Receiving an SMS

How the phone handles incoming SMS messages, including linked messages.

Incoming message list

Accessing and managing received SMS messages.

Opening the incoming message list with the key

Method to view incoming SMS messages using a specific key.

Opening the incoming message list via the SMS menu

Alternative way to access the incoming SMS list through the main menu.

Deleting the incoming message list

Clearing all received SMS messages from the inbox.

Replying to or forwarding SMS messages

Options for responding to received SMS messages.

Forwarding an SMS

How to send a received SMS message to another recipient.

Copying a displayed number to the directory

Saving the sender's number from an SMS into the phone directory.

Copying/dialling numbers from an SMS text

Using phone numbers found within SMS messages for calls or saving.

Changing the character set

How to select different character sets for writing SMS messages.

Notification by SMS

Setting up SMS alerts for missed calls or answer machine messages.

Saving the notification number

Entering the phone number that will receive SMS notifications.

Setting the notification type

Configuring which events trigger an SMS notification.

SMS mailboxes

Information on setting up and managing personal SMS mailboxes.

Setting up and changing a personal mailbox

Managing personal SMS mailboxes, including activation, PIN, and naming.

Sending an SMS to a personal mailbox

How others can send SMS messages to your personal mailbox.

Setting SMS centres

Configuring the phone to use specific SMS service centres.

Sending an SMS through another SMS centre

How to send SMS using a different active SMS centre.

SMS on a PABX

Specific considerations for sending and receiving SMS messages on a PBX system.

Activating/deactivating SMS function

Enabling or disabling the entire SMS feature on the phone.

SMS troubleshooting

Common SMS errors and their solutions.

Operating the answer machine of the Gigaset C475 base station

Announcement mode

Explains the two modes: Ans. & Record and Announce Only.

Operation via the handset

How to use the handset to interact with the answer machine.

Activating/deactivating the answer machine

Steps to turn the answer machine feature on or off.

Recording a personal announcement/announce only

Guide on how to record a custom greeting message.

Playing back announcements

Listening to recorded greetings, both personal and pre-recorded.

Deleting announcements/announce only

Removing custom greeting messages from the answer machine.

Selecting announcement mode

Choosing between automatic message recording or announcement-only modes.

Setting "Answer & Record" or "Announce Only" by toggling

How to schedule changes between the two announcement modes.

Playing back messages

How to listen to recorded voice messages.

Playing back new messages

Accessing and listening to messages received since the last check.

Playing back old messages

Listening to messages that have already been played back.

Stopping and controlling playback

Features for pausing, resuming, skipping, and restarting message playback.

Marking a message as "new"

Re-marking a previously played message as unread.

Copying the telephone number of a message to the directory

Saving the caller's number from a message directly into the phone's directory.

Deleting messages

Methods for removing voice messages from the answer machine.

Deleting all old messages

Removing all previously heard messages.

Deleting individual old messages

Removing specific old messages one by one.

Picking up a call from the answer machine

How to interrupt recording and speak directly to a caller.

Diverting an external call to the answer machine

Forcing incoming external calls to the answer machine, even if deactivated.

Activating/deactivating two-way recording

Enabling the feature to record both sides of a conversation.

Activating/deactivating call screening

How to listen to incoming messages as they are being recorded.

Permanently activating/deactivating call screening

Setting the call screening feature to be always on or off.

Switching off call screening for the current recording

Temporarily disabling call screening for a single incoming message.

Setting up the answer machine

Customizing various settings for the answer machine's operation.

Call acceptance/charge saving function for remote operation

Configuring when the answer machine accepts calls, including an automatic mode.

Setting the recording time

Adjusting the maximum duration allowed for recorded messages.

Setting the recording quality

Choosing the desired quality level for recorded messages, affecting time.

Resetting fast access for the answer machine using key 1

Configuring key 1 for quick access to the answer machine or network mailbox.

Operating when on the move (remote control)

How to manage the answer machine remotely via another phone or SMS.

Calling the answer machine and playing back messages

Instructions for remotely accessing the answer machine and listening to messages.

Activating the answer machine

Steps to activate the answer machine remotely.

Initiating ringback from the answer machine with SMS and listening to messages

Using SMS to trigger a callback from the answer machine for message playback.

Using the network mailbox

Configuring fast access for the network mailbox

Setting up quick access to the network mailbox feature.

Configuring fast access for the network mailbox and entering the network mailbox number

Detailed steps for setting up fast access and inputting the mailbox number.

Calling the network mailbox

How to access the network mailbox service.

Viewing the network mailbox report

How notifications for new network mailbox messages are received.

Using several handsets

Registering handsets

Guide on adding new handsets to the base station.

Automatic registration of Gigaset C47H to Gigaset C470/C475

Simple process for automatic handset registration.

Manual registration of Gigaset C47H to Gigaset C470/C475

Steps for registering handsets manually if automatic fails.

Registering other handsets

How to register handsets from other manufacturers or older models.

Deregistering handsets

Removing registered handsets from the base station.

Locating a handset ("paging")

Function to find a misplaced handset by making it ring.

Ending paging

How to stop the paging sound.

Making internal calls

How to call other registered handsets within the same system.

Calling a specific handset

Dialing a particular handset directly.

Calling all handsets ("group call")

Making a call to all registered handsets simultaneously.

Ending a call

How to terminate an internal call.

Transferring a call to another handset

Moving an external call to another registered handset.

Internal consultation/conference calls

How to involve an internal participant in an external call or create a conference call.

Ending a conference call

Procedures for ending a conference call, including participant actions.

Accepting/rejecting call waiting

How to handle incoming calls while already on a call.

Ending an internal call, accepting an external call

Switching from an internal call to an external one.

Rejecting the external call

How to decline an incoming call while remaining on an internal call.

Listening in to an external call

Allowing an internal user to listen to an ongoing external call.

Activating/deactivating internal listening-in

Enabling or disabling the feature for internal call monitoring.

Changing the name of a handset

Customizing the displayed name for each registered handset.

Changing a handset's internal number

Modifying the assigned internal number for a handset.

Using a handset as a room monitor

Functionality to use a handset as a baby monitor or remote listening device.

Activating the room monitor and entering the number to be called

Setting up the room monitor feature and specifying the destination number.

Setting the handset

Changing a set external destination number

Modifying the pre-set external number for functions like room monitoring.

Changing a set internal destination number

Modifying the pre-set internal number for functions like room monitoring.

Deactivating the room monitor remotely

Steps to turn off the room monitor function remotely.

Quick access to functions

How display keys can be customized for faster access to features.

Changing display key assignments

Reassigning the default functions of the handset's display keys.

Starting a function

How to activate functions assigned to display keys.

Changing the display language

Selecting the language for all on-screen text displays.

Setting the display

Adjusting display settings like colour schemes and contrast.

Setting the screen picture

Choosing a custom picture or clock for the idle display.

Changing the screen picture

How to select and change the screen picture displayed on the handset.

Setting the display backlight

Activating or deactivating the display's backlight.

Activating/deactivating auto answer

Enabling or disabling automatic call answering when lifting the handset.

Changing the handsfree/earpiece volume

Adjusting speaker and earpiece volume levels.

Setting the volume during a call:

How to adjust volume levels while actively on a call.

Changing ringer tones

Selecting different ringtones and volumes for various call types.

Settings for individual functions

Customizing ringtones and volumes for specific call types (external, internal).

Same ringer tone for all functions

Applying a single ringer tone and volume to all call types.

Activating/deactivating the ringer tone

Muting or unmuting the handset's ringer.

Deactivating the ringer tone permanently

Permanently disabling the ringer for the handset.

Reactivating the ringer tone

Turning the handset's ringer back on.

Deactivating the ringer tone for the current call

Temporarily silencing the ringer for an ongoing call.

Activating/deactivating the alert tone

Using a short beep instead of a ringer tone for calls.

Activating/deactivating advisory tones

Managing various tones that signal events like key presses or low battery.

Setting the alarm clock

Configuring the alarm clock feature, including time and melody.

Activating/deactivating the alarm clock and setting the wake-up time

How to enable/disable the alarm and set the desired wake-up time.

Deactivating the wake-up call/repeating after a pause (snooze mode)

Stopping the alarm or using the snooze function.

Setting the base station

Restoring the handset to the factory settings

Resetting individual handset settings to their original defaults.

Protecting against unauthorised access

Securing base station settings with a personal PIN.

Changing the system PIN

How to change the 4-digit system PIN for base station security.

Resetting the system PIN

Procedures to reset the system PIN if forgotten.

Changing ringer tones

Adjusting base station ringer volume and melody for external calls.

Activating/deactivating music on hold

Enabling or disabling the music-on-hold feature for calls.

Repeater support

Activating repeater mode to extend the base station's range.

Restoring the base station to the factory settings

Resetting all base station settings to their original factory defaults.

Connecting the base station to PABX

Dialling modes and recall

Configuring dialling methods (DTMF/DP) and recall settings for PABX compatibility.

Changing the dialling mode

Selecting between touch tone or pulse dialling.

Setting recall

Adjusting recall timing parameters for PABX connections.

Saving an access code (outside line code)

Entering an access code required for external calls on a PABX.

Setting pauses

Configuring pause durations after line seizure or access codes.

Changing pause after line seizure

Adjusting the pause length after the line is seized.

Changing a dialling pause (pause after access code)

Setting pause duration after entering an access code.

Switching temporarily to touch tone dialling (DTMF)

How to switch to DTMF dialling for specific connections like network mailboxes.

Appendix

Care

Recommendations for cleaning and maintaining the device.

Contact with liquid

Steps to take if the handset comes into contact with liquid.

Questions and answers

Troubleshooting common problems and where to find solutions.

Service (Customer Care)

Online Support and Contact

Information on accessing online support, FAQs, user guides, and customer service contact details.

Authorisation

Guarantee Certificate United Kingdom

Details of the manufacturer's warranty terms and conditions for the product.

Specifications

Recommended batteries

List of recommended battery types for optimal performance and longevity.

Handset operating times/charging times

Table detailing standby, talk, and charging times based on battery capacity.

Base station power consumption

Information on the power usage of the base station in different modes.

Notes on the user guide

General specifications

Technical details of the DECT standard, radio frequency, and transmission power.

Example of a menu input

Explanation of how menu steps are presented in abbreviated form.

Example of multiple line input

Illustration of how to enter data across multiple lines, using icons.

Writing an SMS/names

How to enter letters and characters for SMS messages and directory entries.

Standard characters

Table showing character input methods for different keys.

Writing and editing text

Rules for text input, cursor control, and character insertion.

Accessories

Gigaset Handsets

Overview of available Gigaset handset models and their features.

Gigaset C47H handset

Features specific to the Gigaset C47H handset model.

Gigaset S67H handset

Features specific to the Gigaset S67H handset model.

Gigaset Handset SL37H

Features of the Gigaset SL37H handset, including Bluetooth and PC interface.

Gigaset Handset SL56

Features of the Gigaset SL56 handset, including voice dialling and PC interface.

Gigaset Handset S45

Features of the Gigaset S45 handset, including colour display and room monitor.

Gigaset Handset E45

Features of the Gigaset E45 handset, including dust/splashproof casing.

Wall-mounting the base station

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Siemens Gigaset C450 User Manual

Table of Contents

Questions and Answers:

Siemens Gigaset C450 Specifications

Summary

The handset at a glance

Siemens Gigaset contact numbers

The base station at a glance

Safety precautions

General safety warnings

First steps

Pack contents

Installing the base station

Range and reception strength

Connecting the base station

Setting up the handset for use

Attaching the belt clip

Opening the battery cover

Placing the handset in the base station and registering

Headset socket

Initial charging and discharging of batteries

Setting the date and time

Display in idle status

Operating the handset

Activating/deactivating the handset

Activating/deactivating the keypad lock

Control key

Display keys

Reverting to idle status

Menu guidance

Correcting incorrect entries

ECO DECT

Activating/deactivating eco mode:

Menu tree

Making calls

Making an external call

Ending a call

Accepting a call

Calling Line Identification

Call display with CLIP/CLI

Switching between earpiece and handsfree mode

Muting

Making calls using network services

Setting functions for the next call

Setting functions for all subsequent calls

Functions during a call

Functions after a call

Activating/deactivating the network mailbox

Using the directory and lists

Directory/call-by-call list

Saving a number in the directory

Saving a number in the call-by-call list

Order of directory entries

Selecting entries in the directory and call-by-call lists

Dialling with the directory/call-by-call list

Managing directory/call-by-call entries

Viewing entries

Editing entries

Using other functions

Using quick dial keys

Sending the directory/call-by-call list to another handset

Copying a displayed number to the directory

Copying a number from the directory

Last number redial list

Manual last number redial

Managing entries in the last number redial list

Opening lists with the message key

Incoming SMS message list

Call history

Setting the call history type

Answer machine list (Gigaset C475 only)

Making cost-effective calls

Linking call-by-call numbers with one number

Automatic network provider preselection (preselection)

Saving preselection numbers

Save or change entries in the preselection lists

Temporarily cancelling preselection

Permanently deactivating preselection

SMS (text messages)

Writing/sending an SMS