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
11/12/2025
Dalet, a leading provider of cloud-native, end-to-end media workflow solutions, ...
27/11/2025
LONDON Vizrt has added several AI-driven advanced features offering improved speed, intelligence and accuracy in the newest version of its media asset managemen...
27/11/2025
Prime Video has launched AI-powered video season recaps in a beta version for select English-language Prime Original series in the U.S., a move Amazon is callin...
27/11/2025
27 Nov 2025
GSMA brings M360 Eurasia 2026 to Samarkand in partnership with VEON...
27/11/2025
Tahar Rahim and Izuka Hoyle star in the gripping six-part Sky Original from Acad...
27/11/2025
Thursday 27 November 2025
Sky Arts Reveals the Nation's Greatest Basslines - and Queen Reign Supreme
The UK's most iconic basslines have been revealed...
27/11/2025
Back to All News
Stranger Things 5': Prepare for One Last Adventure With O...
27/11/2025
The media industry has a paradox at its core. It's an industry built on light, color and imagination, yet behind the scenes, it's powered by one of the ...
27/11/2025
Rating reflects rating progress across areas including policies, diversity & inclusion, health & safety and Net Zero leadership
Winchester, UK, 27 November 202...
27/11/2025
What are the industry standards for Retail Media? Kathryn explains that certification is based on the IAB Europe Retail Media Measurement Standards and the IAB ...
27/11/2025
World champion boxer and Irish sporting icon Katie Taylor will be in studio this...
27/11/2025
Roblox, one of the world's most popular online gaming platforms for primary ...
27/11/2025
Black Friday is leveling up. Get ready to score one of the biggest deals of the season - 50% off the first three months of a new GeForce NOW Ultimate membership...
26/11/2025
SVG Sit-Down: Prime Video EP Mike Muriano Previews Massive Black Friday Slate Fe...
26/11/2025
A cinematic snow sculpture at the 1995 Sundance Film Festival. Photo by Randall Michelson...
26/11/2025
Book podcasts are booming. On Spotify, you'll find everything from celebrity book clubs to deep dives with bestselling authors. And in markets where audiobo...
26/11/2025
Mumbai, November 24, 2025: In a first-of-its-kind initiative, JioStar, in collab...
26/11/2025
LONDON Factual content producer ITN Productions has launched a new low-latency IP gallery for news bulletins....
26/11/2025
MIAMI TelevisaUnivision said it struck a new multiyear distribution agreement with YouTube TV that includes distribution of TelevisaUnivision's U.S. network...
26/11/2025
OpenDrives, Inc., a leader in software-defined data storage and data services, today announced the launch of the Atlas Corporate Creative Solution. This new Atl...
26/11/2025
Disguise, the industry-leading company powering the world's biggest live performances, is partnering with pioneering LED wall manufacturer DVS to give atten...
26/11/2025
HighField AI, the pioneer in agentic and multimodal automation for broadcast and media production, today announced the expansion of its global channel partner n...
26/11/2025
As high-stakes Premier League fixtures approach and additional premium content launches, with MONO positioning themselves to dominate Thailand's sports stre...
26/11/2025
Hosting a wide variety of events from high-intensity NHL games to complex live music concerts and major entertainment productions, Montreal's 21,000 capacit...
26/11/2025
Vizrt, the leader in live production technology revolutionizing viewer engagement and experience, releases AI-driven advances focusing on speed, intelligence, a...
26/11/2025
ITN Productions, an award-winning factual content producer, today launched a new low-latency IP gallery for news bulletins. Responsible for delivering a leading...
26/11/2025
Ikegami reports ongoing advances throughout 2025 in developing and delivering coordinated television production solutions that maximize quality, versatility and...
26/11/2025
Following the Nov. 21 blackout of NBCUniversal channels on Fubo, the two sides have traded barbs about their inability to reach a new carriage deal....
26/11/2025
LONDON As TV sports rights become increasingly important for both broadcasters and streamers, Ampere Analysis predicts global investment in the genre will surpa...
26/11/2025
LOS ANGELES Vubiquity said it has achieved the Amazon Web Services (AWS) Media & Entertainment Competency as part of the AWS Partner Network (APN). This designa...
26/11/2025
WASHINGTON The Federal Communications Commission's Enforcement Bureau said it has entered into a consent decree with Comcast calling for the cable company t...
26/11/2025
Berklee Named to the Hollywood Reporters Top Music Schools List The publication highlights the college's screen scoring program, industry partnerships, and ...
26/11/2025
Back to All News
Animated Series Love Through a Prism' Casts New Light on ...
26/11/2025
Back to All News
NALIP Unveils Fifth Cohort of Director Incubator
Social Impact
26 November 2025
United States
Link copied to clipboard
The National Assoc...
26/11/2025
YouView Achieves Greenly Gold Certification for SustainabilityNov 26, 2025
YouView is proud to announce a Gold Certification award from Greenly for our perform...
26/11/2025
Back to All News
Netflix Deepens Partnership with Taiwan's 62nd Golden Hors...
25/11/2025
Tracy Bonareri Onchoke, an investigative journalist from Kenya is the winner of the Thomson Foundation's Young Journalist Award 2025.
The 26-year-old-sele...
25/11/2025
SVG All-Stars: Blayke Scheer, Senior Director, Creative Content, YES NetworkThe Indiana alum has turned storytelling into an artform for more than two decadesBy...
25/11/2025
Op-Ed: With FCC's C-Band Auction on the Horizon, Broadcasters Need Proven, C...
25/11/2025
Analysis: Is Baller League really the future of sport? By Callum McCarthy, Editor-at-Large
Tuesday, November 25, 2025 - 10:10
Print This Story
With KSI on...
25/11/2025
Platinum Whitepaper: The Growth of Broadcast in the World of Major Large Scale E...
25/11/2025
SVG Summit 2025 Preview: SVG Women's Sports WorkshopBy Samantha Gabay
Tuesday, November 25, 2025 - 10:27 am
Print This Story | Subscribe
Story Highlig...
25/11/2025
SVG New Sponsor Spotlight: CacheFly's Matt Levine on the Evolving Role of th...
25/11/2025
Peacock's EA SPORTS Madden NFL Cast Levels Up on Thanksgiving With SkyCam as...
25/11/2025
Mathias Broe attends the 2025 Sundance Film Festival premiere of Sauna at Library Center Theatre. (Photo by Michael Hurcomb/Shutterstock for Sundance Film Fes...
25/11/2025
The best playlists, podcasts, and audiobooks bring a little extra magic to your daily routine. With new features and offerings, Spotify Premium delivers even mo...
25/11/2025
Comprehensive new research confirms what we already knew: Australian music fans love the quality, quantity, and access they have to new and local music on strea...
25/11/2025
Applicable Products
Objectives The purpose of this application note is to give a brief background on 5G (NR) wireless communication an explain the reason a SN...
25/11/2025
Nielsen will now measure both Lionsgate's FAST channel MovieSphere and Movie...
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.
