Circuit switched networks physically connect two endpoints using a communication channel through the network. This utilises a fixed bandwidth for the session whilst the two endpoints remain connected. Packet switched networks offer the ability to split the communication channel into small packets to be sent across the network using multiple routes offering redundancy and increased performance. This utilises dynamic bandwidth management which can be optimised for each connected party and allows for many more services and connections to be active at the same time using the same bandwidth.
In the cellular network GSM (2G) and UMTS (3G) use circuit switching for voice, circuit switched dialup (CSD) and short messaging service (SMS) traffic and use packet switching for GPRS data traffic. In LTE (4G) the entire network uses packet switching and has no capability for circuit switched network support. As a result, the voice and SMS services must be moved over to a packet switched network when using the LTE (4G) network. In addition to this, CSD is no longer supported and GPRS data must be used instead.
Please see Circuit Switched Dialup (CSD) Migration to LTE Application Note' here.
Voice Overview Many applications in use today utilise voice as part of the service offering. This may be to connect two parties together to communicate such as in an elevator emergency failure system, to implement an automated payment service using a dial keypad or report a fault with a system using normal spoken language. Whatever the reason for using the voice service in a cellular system, there are some differences with the LTE network which are described in more detail below.
On legacy devices supporting GSM (2G) and UMTS (3G) services, the voice and SMS components of the system use circuit switching as the transmission channel. For GSM the whole system was built on an analogue infrastructure and digital data was added to the system later with the advance of GPRS packet data. The UMTS system is based on the GSM standard and therefore also supports both digital and analogue components. The UMTS framework allows much higher data rates over GSM but is still based on a similar infrastructure.
LTE on the other hand is entirely digital and has no analogue components at all. Therefore, new methods are used to take advantage of the new features offered by the LTE network as analogue voice calling is no longer possible and the packet switched network must be adopted.
VoLTE (Voice over LTE) Overview The LTE network supports voice and many other additional services in the same way as GSM and UMTS, however, as there is no analogue component the voice must be encoded and sent digitally across the network using packets. The 3GPP body have specified the voice service on LTE which is highly optimised and takes advantage of the additional bandwidth and low latency of the LTE network. This service is called Voice over LTE (VoLTE) and uses the digital packet switched network in a much more efficient way than traditional services. This means that VoLTE can support up to 3 times more voice capacity than previous UMTS networks and up to 6 times more capacity than older GSM networks.
The VoLTE service is provided on LTE over the IP Multimedia System (IMS) network service which is a standardized framework for delivering multimedia services over TCP/IP. It has been developed to allow all content rich media from wireless and wireline applications and allows for advanced services to be provided over the existing infrastructure without the need for individual control functions for each service.
The network provider must support IMS to be able to offer VoLTE as a service to its customers. The IMS framework must be integrated within the network's core architecture and is fundamental to the operation of the network.
Network Usage with Circuit Switch Fall Back (CSFB) With existing GSM (2G) and UMTS (3G) networks, the core functions are built into the application and can be supported with any hardware platform that supports voice and any SIM card that supports voice. This allows for a very simple implementation and calls can be established without any special configuration to the end equipment.
With newer modems that support LTE (4G) in addition to GSM (2G) and UMTS (3G) the firmware in the modem performs a subtle trick to continue having seamless voice support. When connected to the network for transmitting digital packet data, the unit connects to and uses the LTE network. When attempting to dial a voice number the unit automatically switches to UMTS (3G) or GSM (2G) to establish the call. Once the call is finished it reverts to the LTE network. This technology is called circuit switch fall back and is a short-term solution to allow all network providers to offer voice services on the LTE network whilst they implement their own full IMS solution.
This process is fine whilst there are UMTS (3G) and GSM (2G) networks available to use but the analogue networks are being gradually sunset to be replaced entirely with the LTE network.
With the LTE (4G) network it is necessary to configure the device to allow calls to be made using the LTE only network over the IMS service.
SMS Overview The short messaging service (SMS) can be used to send and receive small text messages which can be used in a variety of ways for applications that use the cellular network. The messaging service can be used to configure settings in remote equipment as well as reporting on the current configuration. In addition, the messaging service can inform users directly of a triggered alarm state or indicate when a certain criterion has been met. As with voice, the existing GSM (2G) and UMTS (3G) core functions are built into the system and can be supported with any hardware platform that supports the SMS messaging service and any SIM card that has SMS functio
Europe Stories
05/01/2027
Worlds first 802.15.4ab-UWB chip verified by Calterah and Rohde & Schwarz to be ...
09/10/2026
September 10 2026, 06:00 (PDT) Dolby Expands Dolby OptiView Platform with New Capabilities at IBC 2026
New Sports Intelligence helps providers better unders...
07/10/2026
Dalet, a leading technology and service provider for media-rich organizations, today announced the latest Long-Term Supported (LTS) release of Dalet Flex. Build...
12/09/2026
Latest Obsolete Devices pedal announced
Great Eastern FX Co. have just launched the latest pedal in their Obsolete Devices series, a range of effects pedals...
12/09/2026
September 11, 2026
BUDAPEST & SEATTLE, 10 September 2026 - Qumulo and Colorfron...
12/09/2026
Calrec expands its IP ecosystem with new Type RT console and Apex M6 Modular I/O Platform at IBC 2026 Type RT is the centrepiece of Calrec's news at IBC 202...
11/09/2026
Spark series gains compact modelling stompbox
Positive Grid's Spark amps have become a popular part of the company's line-up, offering a convenient ...
11/09/2026
New flagship sequencing plug-in revealed
Rapid Flow have just launched a new 16-track sequencer plug-in which they say has been designed for total rhythmic...
11/09/2026
Rohde & Schwarz unveils the air-cooled R&S TM1 medium-power UHF transmitter at I...
11/09/2026
Friday 11 September 2026
Sky Sports extends US Open deal to 2030
Sky has agreed a three-year extension to its US Open deal, ensuring Sky Sports & NOW remains ...
11/09/2026
Wuppertal September 11, 2026
A Decade of Innovation: AMP VISUAL TV Builds on Ten Years of MediorNet EvolutionAMP VISUAL TV is continuing the evolution of its ...
11/09/2026
Wuppertal September 11, 2026
Mediacom Deploys Riedel Easy5G for Wireless Camer...
11/09/2026
Wuppertal September 11, 2026
Touring Video Expands Flexible Production Workflows With Riedel MediorNet and hiRiedel Communications today announced that Tourin...
11/09/2026
Wuppertal September 11, 2026
Riedel Technology Powers Record-Breaking Esports World Cup Production in ParisFrom July 6 to Aug. 23, 2026, Paris hosted the Espo...
11/09/2026
Article courtesy of Digital Production
Read the article
With Baselight 8 coming in 2027, the interesting part is not the number of new buttons. Some features...
11/09/2026
It's almost iPhone Pro time. Starting Saturday, September 12, at 1 p.m, cust...
11/09/2026
RT has today announced Benetti Menswear as the sponsor of its 2026 Amgen Irish Open coverage for a sixth consecutive year, further strengthening the heritage c...
10/09/2026
Editing, restoration & mastering suite upgraded Acon Digital Acoustica 8 audio editing restoration mastering software.
Acon Digital have just launched the la...
10/09/2026
Classic synths & drum machines available to play
Based in Reading, UK, Readipop are a music and arts charity with a long track record of innovative, partici...
10/09/2026
Popular model updated & new addition introduced
With many of the models in Neumann's KH family now boasting onboard DSP and support for the company'...
10/09/2026
Improved desktop interface announced
The latest iteration of Arturia's flagship desktop audio interface has just arrived, introducing improved preamps, ...
10/09/2026
Progress needs proof: Rohde & Schwarz showcases its trailblazing test solutions ...
10/09/2026
CUPERTINO, CALIFORNIA Apple today announced iPhone 18 Pro and iPhone 18 Pro Max,...
10/09/2026
CUPERTINO, CALIFORNIA Apple today introduced Apple Watch Ultra 4 - the ultimate ...
10/09/2026
CUPERTINO, CALIFORNIA Apple today introduced Apple Watch Series 12, engineered w...
10/09/2026
The beloved duo are back with big challenges and even bigger laughs as they discover if you're ever truly too old to try something new.
Previous praise for...
10/09/2026
Thursday 10 September 2026
Sky News Defence Insider app launches as new researc...
10/09/2026
Thursday 10 September 2026
Award-winning network Sky Mobile to offer Apple iPho...
10/09/2026
Thursday 10 September 2026
Sky unveils gripping teaser for The Good Daughter, coming this NovemberTurn on cookies to view this content. Go to Privacy options a...
10/09/2026
Harmonic Leads the New Era of Broadband Connectivity at SCTE TechExpo 2026 Showcase Spotlights Include:
New cOS SensAI intelligence fabric unleashing data-pow...
10/09/2026
RT to Broadcast Amgen Irish Open free-to-air
New multi-year agreement will see RT continue to bring the Amgen Irish Open to Irish audiences
Ryder Cup hig...
10/09/2026
More than 30 women report allegations of sexual harassment, misogyny and bullying within National Ambulance Service
Tonight on RT Prime Time, 9:35pm, RT One ...
10/09/2026
Series 3 of Nero's Class begins Friday 11 September on RT Listen
The third...
09/09/2026
New parts aimed at hip-hop and pop productions
The latest update to Celemony's innovative virtual session musician expands the collection of built-in in...
09/09/2026
Save up to 40% until 21 September 2026
Sonarworks are currently running their Autumn Sale, with discounts of up to 40% currently available across their rang...
09/09/2026
Upcoming title officially launches in September 2026
Bjooks' celebrations for this year's 909 Day will be welcome news amongst drum machine lovers, ...
09/09/2026
** MEDIA ALERT **
NARUTO Takes the Stage at New York Comic Con 2026 Special Panel to Feature Franchise News, First-look Footage and Appearances by Japanese ...
09/09/2026
CUPERTINO, CALIFORNIA Apple today introduced iPhone Duo, the first foldable iPhone. Opened, it is the thinnest iPhone ever, with a 7.6-inch inner display that p...
09/09/2026
CUPERTINO, CALIFORNIA Apple today announced AirPods 5, delivering the industry&#...
09/09/2026
Chennai/Luxembourg, 9 September 2026 - SES, a leading space solutions company, today announced the inauguration of its new office in Chennai, India, marking a s...
09/09/2026
September 9 2026, 22:35 (PDT) Cinema Sunshine Becomes Japan's First Exhibit...
09/09/2026
Wednesday 9 September 2026
Tom Daley adds final stitch to giant Baa-Ewe' t...
09/09/2026
Red Seat Ventures Integrates Barometer into Speakeasy to Maximize Podcast Revenu...
09/09/2026
Baselight-powered color comes natively to Media Composer, connecting creative de...
09/09/2026
RT brings three packed days of live radio, entertainment, news, weather and fun
Join RT Radio 1: Morning Ireland, Oliver Callan, Today with David McCullagh,...
08/09/2026
Built for rap producers, by rap producers
Sauceware Audio, the independent plug-in company founded by Grammy-nominated producer Jacob (Travis Scott, 21 Sava...
08/09/2026
Classic Sound Techniques design revived
Warm Audio's latest release delivers a meticulous recreation of the preamp circuitry employed by the Sound Techn...
08/09/2026
Latest soft synth inspired by the Memorymoog
XILS Lab have just launched a software instrument that draws its inspiration from Moog's iconic Memorymoog,...
08/09/2026
September 08, 2026 NORTHRIDGE, Calif. - Soundcraft today announced the launch of its Signature Plus Series Analog Connected Mixing Consoles. As the next genera...
Circuit switched networks physically connect two endpoints using a communication channel through the network. This utilises a fixed bandwidth for the session whilst the two endpoints remain connected. Packet switched networks offer the ability to split the communication channel into small packets to be sent across the network using multiple routes offering redundancy and increased performance. This utilises dynamic bandwidth management which can be optimised for each connected party and allows for many more services and connections to be active at the same time using the same bandwidth.
