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
Most recent headlines
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
In its sixth year, the broadcaster's coverage has become a global brand and ...
01/06/2026
Designed to solve a common problem in broadcasting, the automated workflow detects, identifies, removes, and documents copyrighted music
AudioShake has introdu...
01/06/2026
The sports-analytics company combines its data with proprietary AI to help leagu...
01/06/2026
Category line-up & sponsors announced
Photo: Paul Clarke
The Production Music Awards (PMA) have announced that submissions are now officially open ahead of...
01/06/2026
New hybrid sample/synthesis instrument revealed
Excite Audio have just released the latest instalment in their Evolve series, which has been developed in co...
01/06/2026
Latest TONEX expansion captures three rare vintage amps
The newest addition to IK Multimedia's ever-growing TONEX line-up introduces a set of three incr...
01/06/2026
Musically intelligent soft synth gets upgraded
Scaler Music will be probably be best known to many for their music theory tools, but their product range al...
01/06/2026
SBS confirms its broadcast sponsors for FIFA World Cup 2026
1 June, 2026
Media releases
SBS has secured Hyundai, Hisense, Macca's, Rexona, bet365, Com...
01/06/2026
Rohde & Schwarz Satellite Industry Days 2026 guided by the motto From Earth to ...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Marshall Electronics is showcasing a comprehensive lineup of next-generation POV cameras, purpose-built to power today's connected AV environments, at InfoC...
01/06/2026
Adobe Announces Concept to Vector
Deepa Subramaniam June 1, 2026
0 Comments
One of the biggest frustrations we hear from designers is how difficult it...
01/06/2026
Vampire Feature Night Patrol Graded with DaVinci Resolve Studio
Brie Clayton June 1, 2026
0 Comments
Colorist shapes dark, gritty tone for horror thri...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
01/06/2026
Mardi 2 juin 14h00
FilmLight (ARRI), 10 rue Ren Boulanger, 75010 Paris
Rejoignez-nous pour d couvrir comment FLAPI (l'API FilmLight) peut transformer e...
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...
31/05/2026
Olivia P rez-Collellmir to Premiere Original Work at Gaud Centennial in Barcelona The Berklee graduate and faculty member will debut her choral symphony with...
31/05/2026
Back to All News
Netflix Wins 15 Awards at the Canadian Screen Awards - See Pho...
31/05/2026
Taiwan is home to more than 500 NVIDIA ecosystem partners. More than 1 million N...
31/05/2026
As factories move from isolated automation to plant-wide intelligence, manufacturers need AI systems that can connect live machine signals, quality systems, wor...
31/05/2026
The NVIDIA AI Cloud ecosystem is accelerating the global buildout of AI factory infrastructure. Partners are expanding capacity to meet growing demand from ente...
30/05/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
30/05/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
30/05/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
30/05/2026
Zero in on one that says yes (and no)
Andy Marken May 29, 2026
0 Comments
Hero image courtesy of Deposit Photos
For content creators the most difficu...
29/05/2026
With InfoComm 2026 just weeks away, NDI is giving attendees plenty of reasons to...
29/05/2026
Reaffirming a partnership that has defined Canadian sports broadcasting since 19...
29/05/2026
Mobile/tablet is No. 2 device for watching TV, suggesting that the sports-production industry needs to take another look at the format
Ring Digital's Sprin...
29/05/2026
Berliner Ensemble, one of Berlin's five major theater companies, has expande...
29/05/2026
Solid State Logic will showcase its new compact, fly-away TCA Tour audio product...
29/05/2026
Gerald (Jerry) Pierce, a pioneering technologist who helped shape the digital transformation of the motion picture industry, passed away last month on April 12 ...
29/05/2026
Paramount+ will be the English-language U.S. home for Barclays Women's Super...
29/05/2026
Further strengthening its virtualisation strategy to fully support broadcasters ...
29/05/2026
Swiss broadcaster Canal Alpha has deployed Harmonic's award-winning, software-based XOS Advanced Media Processor to modernize playout operations across cant...
29/05/2026
PTZOptics will showcase a new generation of intelligent video workflows at InfoComm 2026, June 17-19, Las Vegas. Visitors to booth N8227 will see how PTZOptics ...
29/05/2026
Arizona's Family has launched the Arizona's Family Sports (AZFS) streaming app, a new direct-to-consumer destination for live, local sports. The app is ...
29/05/2026
Starting in 2027, DAZN will be the exclusive home of The Canadian Football Leagu...
29/05/2026
Comcast Business has detailed the advanced network infrastructure it has deploye...
29/05/2026
In two-day event, leaders from academia and industry explored solutions to chall...
29/05/2026
The Basketball Tournament (TBT), now entering their 13th year of competition, ha...
29/05/2026
Roku has launched FOX One as a Premium Subscription on The Roku Channel in the U.S. Roku customers can now subscribe to FOX One using their Roku account for liv...
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.
