[Glossary](https://telxpress.com/glossary/) / Connectivity # SD-WAN **SD-WAN** (software-defined wide area network) is a service that combines two or more internet connections at a site, steers each application over the best path and fails over automatically when one connection degrades. - Connectivity - Updated October 11, 2026 - Written by the Telxpress advisory team 01 In depth ## What it is, why it matters and *what to ask a vendor* An SD-WAN appliance or cloud service sits between your network and your internet connections (fiber, cable, fixed wireless, cellular). It measures each path continuously, sends voice and video over the cleanest one, keeps a call alive when a connection fails, and manages branch offices from one console. Many services add security functions such as firewalling and content filtering. For a growing business with cloud phones, video meetings and AI agents, the internet connection is now the phone line, and a single connection is a single point of failure. SD-WAN turns two inexpensive connections into a reliable one and makes a new branch a shipped appliance rather than a project. Ask a provider which connections and carriers they support, how fast failover is and whether an active call survives it, how the service prioritizes voice, what the monthly cost is per site, who monitors it and responds to alerts, and whether the security features replace or duplicate your firewall. Carriers such as TPx offer managed SD-WAN; Telxpress designs and supports it with the connections underneath. 02 Related terms ## Terms that usually come up *alongside it* - Connectivity ### [Failover](https://telxpress.com/glossary/failover/) Failover is the automatic switch to a backup connection, device or route when the primary one fails, so that phones, payments and cloud applications keep working through an internet or equipment outage. - Connectivity ### [Dedicated internet access](https://telxpress.com/glossary/dedicated-internet-access/) Dedicated internet access (DIA) is a business internet service whose full bandwidth is reserved for one customer, with a service-level agreement for uptime, latency and repair time, unlike shared broadband. - Connectivity ### [Fixed wireless](https://telxpress.com/glossary/fixed-wireless/) Fixed wireless is business internet delivered by a radio link between an antenna on your building and a nearby tower or base station, used where fiber is unavailable or as an independent backup connection. - Network ### [QoS (quality of service)](https://telxpress.com/glossary/qos/) Quality of service (QoS) is the network configuration that identifies time-sensitive traffic such as voice and video and gives it priority over downloads and backups, so calls stay clear when the network is busy. 03 At Telxpress ## Where this shows up *at Telxpress* The pages and articles where this term does real work: what we advise, build and support. - Page ### [Business Internet, Fiber, SD-WAN & Wi-Fi](https://telxpress.com/solutions/business-technology/connectivity/) Business internet, fiber, SD-WAN, Wi-Fi and carrier services for Orange County offices, selected and managed by one local partner with 24/7 support. - Article ### [Boost Your VoIP Reliability: How SD-WAN Keeps Calls Clear](https://telxpress.com/insights/boost-your-voip-reliability-how-sd-wan-transforms-communication/) How SD-WAN keeps business phone calls clear by steering voice over the healthiest connection, prioritizing it and failing over automatically, and when a simpler setup is enough. - Page ### [Business Networking, Firewalls & Managed Wi-Fi](https://telxpress.com/solutions/business-technology/networking/) Switching, routing, Fortinet firewalls, Ubiquiti and Cisco Meraki Wi-Fi and managed network services for offices that depend on reliable connections. Next step ## Want This Applied *to Your Business?* Book a free 30-minute AI readiness consultation. You'll leave with three AI opportunities specific to your business, whether you work with us or not. [Book My Free Consultation](https://telxpress.com/book/) [Take the Free AI Readiness Assessment](https://telxpress.com/ai-readiness/) [Or call 24/7: (949) 861-4500](tel:+19498614500) Last reviewed: October 11, 2026. Published by Telxpress, Irvine, CA.