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 ...
04/08/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
04/07/2026
April 7 2026, 19:00 (PDT) Detective Conan: Fallen Angel of the Highway Opens in...
01/06/2026
January 6 2026, 05:30 (PST) Dolby Sets the New Standard for Premium Entertainment at CES 2026
Throughout the week, Dolby brings to life the latest innovatio...
08/05/2026
One-button synth generates random four-track ideas
Cyma Forma and French artist Bambounou have announced RND synth, a compact hardware synthesizer built aro...
08/05/2026
Portable four-layer granular and sampling instrument
Tasty Chips have announced the GR-2, a new granular synthesizer and sampling instrument that combines e...
08/05/2026
Video Show Report
Video of SUPERBOOTH 26: Polyend Drums
Polyends big announcement for Superbooth 2026 is the Drums, a new drum machine that features both ...
08/05/2026
Deal agreed as NI enters new chapter
Native Instruments CEO Nick Williams has announced that a definitive agreement has been signed for the company to be ac...
08/05/2026
Video Show Report
Video of SUPERBOOTH 26: Erica Bullfrog Drums
The Bullfrog Drums is the latest collaboration between Erica Synths and Richie Hawtin, and ...
08/05/2026
In our latest blog, Tim Pearson reflects on the recent launch of Play Snooker, the new digital home of snooker by the World Professional Billiards and Snooker A...
08/05/2026
Pete reunites with Dogs Trust for a fourth series and a two-part overseas special
London, Friday 8th May 2026: The award winning factual entertainment series P...
08/05/2026
Wuppertal May 8, 2026
Riedel to Support Glasgow 2026 as Official Connectivity Integration Provider Riedel Communications today announced its return as a spons...
08/05/2026
ICG is excited to share news of our official launch in Northern Ireland, marking a significant milestone in the agency's growth.
Led by Digital Marketing M...
08/05/2026
Over the past ten years, Thames Water, in partnership with Arqiva, has installed more than 1.2 million smart meters, creating one of the most extensive advanced...
07/05/2026
Journalists reporting on Sudan are working in one of the most complex and fast-m...
07/05/2026
Seit dem Start im Jahr 2023 hat DJ (Beta) das personalisierte H rerlebnis von 94...
07/05/2026
Da quando stata presentata nel 2023, DJ (beta) ha aiutato a definire un'esperienza d'ascolto pi personalizzata per 94 milioni di utenti Spotify Premi...
07/05/2026
Since launching in 2023, DJ (beta) has helped shape a more personalized listenin...
07/05/2026
Desde o lan amento em 2023, o DJ (beta) j ajudou a deixar a experi ncia de ouvi...
07/05/2026
From our earliest days, Spotify has been built on a simple principle: Great audio should be easy to reach. It's what's driven us to expand from music to...
07/05/2026
Asian and Pacific Islander artists continue to shape the global soundscape, pushing creative boundaries and connecting with fans worldwide. This Asian & Pacific...
07/05/2026
Company announce long-requested choir instrument
In the latest expansion of their Symphonic Elements series, UJAM have introduced an all-new vocal instrumen...
07/05/2026
Modular-inspired sound generation with digital control
Buchla have introduced Ziggy, a new compact synthesizer built around the company's complex oscill...
07/05/2026
Combines analogue voices with digital synthesis and sequencing
Polyend have announced Drums, a new hybrid analogue and digital drum machine that combines sy...
07/05/2026
Control surface now officially supports four DAWs
When Nektar launched the Panorama CS12 control surface, it worked exclusively with Apple's Logic Pro, ...
07/05/2026
In the first quarter 2026, SGL Carbon generated consolidated sales of 184.5 million, which was 49.8 million, or 21.3%, lower than in the prior year (Q1 2025: ...
07/05/2026
Rohde & Schwarz and Greenerwave achieve precise and fast ESA antenna characteriz...
07/05/2026
January 8, 2024
Colorfront (colorfront.com), a leader in high-performance, on-s...
07/05/2026
February 9, 2024
Colorfront (colorfront.com), the multi-award-winning pioneer i...
07/05/2026
March 20, 2024
NAB 2024, Las Vegas - Colorfront (colorfront.com), the multi-awa...
07/05/2026
April 1, 2025
CINEMACON, APRIL 1, 2025 - Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming syste...
07/05/2026
June 15, 2025
Colorfront (colorfront.com), an Academy and Emmy Award-winning de...
07/05/2026
June 15, 2025
Colorfront participated in the ICTA Barcelona Cinema Technology Summit on Sunday, June 15, 2025. Held at The Phenomena Experience, the event feat...
07/05/2026
July 1, 2025
Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming systems for motion pictures, OTT,...
07/05/2026
July 1, 2025
Passion and dedication will take you places. Come with us on a short trip to the heart of India, where Annapurna Studios is living-up to the inspi...
07/05/2026
July 3, 2025
Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming systems for motion pictures, OTT,...
07/05/2026
September 1, 2025
IBC 2025, Amsterdam - Colorfront (colorfront.com) - the Acade...
07/05/2026
April 17, 2026
LOS ANGELES - April 17, 2026 - Colorfront today announced Colorf...
07/05/2026
April 23, 2026
NAB 2026, Las Vegas - the Academy and Emmy Award-winning develop...
07/05/2026
Comscore to Announce First Quarter 2026 Financial ResultsRESTON, Va., May 7, 2026 - Comscore, Inc. (Nasdaq: SCOR), a trusted partner for planning, transacting a...
07/05/2026
Thursday 7 May 2026
Sky continues Sphere Abacus partnership with The Death of S...
07/05/2026
Thursday 7 May 2026
Sky Confirms Saturday Night Live UK will return this September for Series Two
Saturday Night Live UK will return for a second series, as S...
07/05/2026
Save 20% on the Sky Glass Gen 2 and Sky Glass Air TVsThursday 7 May 2026
How to watch the World Cup on Sky Glass
Tune into the World Cup on the BBC and ITV vi...
07/05/2026
Production sound mixer Dirk Sciarrotta has mixed Family Feud for 28 seasons. Thats up to 200 syndicated episodes per year, plus primetime celebrity specials - a...
07/05/2026
As audience expectations have evolved, Owen has stopped trying to hide microphones or excuse amplification. Instead, he treats sound as a fully immersive part o...
07/05/2026
Well known Irish faces pushed to the edge in new series of
Uncharted with Ray G...
07/05/2026
RT will premiere A Traveller Family, a compelling new documentary exploring the...
06/05/2026
New pricing tiers for vocal/dialogue restoration tool
NoiseWorks Audio's AI-powered vocal and dialogue processing plug-in is now available in three diff...
06/05/2026
Popular mixing & routing software overhauled
Following a recent public beta test, RME have launched the final release version of the powerful mixing and rou...
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.
