
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 ...
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...
02/05/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
01/05/2026
January 5 2026, 18:30 (PST) NBCUniversal's Peacock to Be First Streamer to ...
01/04/2026
January 4 2026, 18:00 (PST) DOLBY AND DOUYIN EMPOWER THE NEXT GENERATON OF CREATORS WITH DOLBY VISION
Douyin Users Can Now Create And Share Videos With Stun...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
12/03/2026
COW Jobs: Editor de V deo - Direct Response, Performance Ads - Brazil, Remote
Brie Clayton March 11, 2026
0 Comments
Editor(a) de V deo (Direct Respon...
12/03/2026
Avatar: Fire and Ash Graded with DaVinci Resolve Studio
Brie Clayton March 11, 2026
0 Comments
Colorist delivers premium cinematic color across 2D, 3D...
12/03/2026
Boston Conservatory to Timoth e Chalamet: We Care About Ballet and Opera Boston Conservatory at Berklee students and faculty respond to the actors recent comm...
12/03/2026
The Late Late Show Show St Patrick's Day special
Dancing with the Stars f...
12/03/2026
GeForce NOW is bringing the game to the Game Developers Conference (GDC), running this week in San Francisco. While developers build the future of gaming, GeFor...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Matrox Video will showcase its vision for the future of live production at NAB 2026 in Las Vegas, April 19-22, highlighting how broadcasters and media organizat...
11/03/2026
Geneva-based technology company, GlobalM SA, is presenting its GMX Distributed Video Gateway, a software-defined IP media transport platform designed to replace...
11/03/2026
Backlight (booth #N2829), the company behind Iconik and Wildmoka, which power video workflows for large media and entertainment organizations, has released the ...
11/03/2026
QuickLink, a leading provider of award-winning video production and remote guest contribution solutions, presents its latest StudioEdge models at The NAB Show ...
11/03/2026
Telestream, a global leader in media workflow technologies, today announced the expansion of Telestream Cloud Services with the introduction of UP, a new cloud-...
11/03/2026
Operative, the preferred advertising management provider for the world's leading media brands, today announced the launch of AOS for digital media, an AI-po...
11/03/2026
Calrec will be located in Central Hall, on Booth C6907
Choice without compromise
The broadcast industry is going through a rapid evolution that s signalling a...
11/03/2026
The new service is hosted and operated entirely in the Netherlands, combining data sovereignty, resilience, scalability, and predictable costs without relying...
11/03/2026
Ease Live, an Evertz company and leader in interactive graphical overlays, today announced the successful deployment of its platform on Red Bull TV for Premier ...
11/03/2026
Mediagenix, a global leader in smart content solutions to profitably connect the right content to the right audience, is advancing its Semantic Intelligence cap...
11/03/2026
Emergent, a leading provider of AI-enhanced media production solutions, today announced the official launch of Fusion, a powerful, no-code application builder d...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
11/03/2026
Utah Scientific today announced the expansion of its Technology Partner Program with the addition of Audinate, Bitfocus, and Skaarhoj, three industry leaders wh...
11/03/2026
DigitalGlue, creator of the creative.space on-premise managed storage platform, today revealed plans to launch creative.space Intelligence (CSI) at NAB 2026 (Bo...
11/03/2026
Maxon, maker of powerful, approachable software solutions for creators working in 2D and 3D design, motion graphics, visual effects, gaming, and more, has annou...
11/03/2026
Composer and Re-recording Mixer Michael Phillips Keeley has built his career around immersive storytelling. Working from his Dolby Atmos-equipped studio, Sound ...
11/03/2026
Leading video software provider Synamedia today announced that YES, the pay-TV subsidiary of the telco Bezeq (TASE: BEZQ), has selected Synamedia Iris to delive...
11/03/2026
As media companies face increasing cost pressures and operational complexity, at the 2026 NAB Show in Las Vegas, Viaccess-Orca (VO), a global leader in OTT / TV...
11/03/2026
Digital Alert Systems, a global leader in emergency communications solutions for media providers, today announced the release of Version 6 software for its DASD...
11/03/2026
First Medium-Earth Orbit (MEO) deployment of the emergency.lu platform for refugees and their host communities' use provides dependable broadband for humani...
11/03/2026
Foundry releases Nuke 17.0
Brie Clayton March 1, 2026
0 Comments
Native Gaussian Splat support, new 3D system based on USD, expanded machine learning ca...
11/03/2026
Preserving UNESCO World Heritage with URSA Cine Immersive
Brie Clayton March 1, 2026
0 Comments
The Explorers turned to France's cultural landmark...
11/03/2026
I Clicked This By Accident And It Made After Effects SO Much Faster
Graham Quince March 1, 2026
0 Comments
Discover how Region of Interest in Adobe A...
11/03/2026
Cine Gear Connect Brings a Focused All-Day Experience to Industry City, NY
Brie Clayton March 4, 2026
0 Comments
Registration is now open for Cine Gea...
11/03/2026
La Vor gine Edited and Finished with DaVinci Resolve Studio
Brie Clayton March 4, 2026
0 Comments
One of Colombia's most ambitious projects goes g...
11/03/2026
SoundMarket Launches 18,000 Tracks of Real Music by Award-Winning Composers for...
11/03/2026
Capta Center Supports NOVO19 Remote Production with Blackmagic Design
Brie Clayton March 5, 2026
0 Comments
The facility provides production and playo...
11/03/2026
DigitalGlue Ends the Post-Production Tax: creative.space Intelligence (CSI) Unif...