Why Erlang is Still the Go-To for Scalable Telecom Systems

25 September 2025

If you’ve ever been on a long phone call, streamed a live event, or yelled at your internet provider because your connection dropped, chances are… you interacted with Erlang in some way. Yeah, really. It’s the quiet genius working behind the scenes, ensuring networks don't collapse under the weight of millions of simultaneous users.

But why on earth is Erlang—an old-school programming language from the '80s—still running the show in modern telecom? Doesn’t it have tech grandkids by now? Shouldn’t it be retired somewhere, sipping piña coladas on a beach with COBOL?

Well, grab your coffee (or piña colada, no judgment), and let’s talk about why Erlang is still the absolute powerhouse for scalable telecom systems.

What Even Is Erlang?

Before we start throwing confetti at Erlang’s greatness, let’s get one thing straight—it’s not a typo for "earl grey tea." Erlang is a programming language created by Ericsson in the 1980s specifically for telecom applications. Yes, the same Ericsson that probably built a good chunk of the mobile infrastructure you're using right now.

Erlang was designed to handle massive amounts of concurrent users (think millions of calls happening at once) while ensuring uptime and reliability. And here’s where it differs from your usual programming suspects.

What Makes Erlang So Good for Telecom?

1. Concurrency: Erlang Laughs at Heavy Traffic

Imagine you’re hosting a party, but instead of 10 guests, you suddenly have 10 million. In most cases, your house (or server) would crash and burn. But Erlang? It was literally built for this.

Erlang's concurrency model is like having millions of tiny, independent bartenders (lightweight processes) that keep serving drinks (data packets) without stepping on each other’s toes. Each process runs independently, so if one goes rogue and spills a drink (crashes), the others keep doing their job.

This is why telecom companies swear by Erlang—it can juggle tons of tasks without slowing down.

2. Fault Tolerance: Because Dropped Calls Are Annoying

What’s worse than bad service? A sudden, unexpected service outage when you're in the middle of an important call.

Erlang was designed with fault tolerance in mind. If a process crashes, it doesn’t bring down the whole system. Instead, Erlang has a built-in "supervising hierarchy" that automatically restarts failing processes faster than you can say, “Can you hear me now?”

For telecom systems handling millions of active users, this is a game-changer. Nobody likes their phone dropping calls like a clumsy waiter drops plates.

3. Scalability: Handling Growth Like a Pro

Erlang is like a modular, build-as-you-go LEGO set. Need to expand capacity? No problem—just spawn more lightweight processes.

Telecom systems need to handle unpredictable spikes—think of the mad rush of calls and messages on New Year’s Eve or when a major sports final is happening. While many systems struggle under pressure, Erlang effortlessly scales up without breaking a sweat.

This is why big-name telecom companies still rely on Erlang. It’s like having an elastic waistband—always ready to stretch when needed.

4. Soft Real-Time Capabilities: Because Milliseconds Matter

Ever tried making a VoIP call or streaming without delays? If yes, then you unknowingly owe Erlang a thank-you card.

Erlang is a “soft real-time” system, meaning it processes tasks fast enough that you don’t even notice delays. Think of it as a barista who makes your coffee lightning-fast, but doesn’t rush so much that they spill all over the counter.

For telecom, where milliseconds can make or break a call’s quality, this is invaluable.

5. Hot Code Swapping: Updates Without Interruptions

Most systems require restarts when updating code. Imagine if your phone provider had to reboot the entire network every time they made a change—it would be chaos.

But Erlang? It allows live updates without shutting down the system.

Think of it like getting a software update on your phone without restarting. This is a huge deal for telecom providers who need to provide continuous service without downtime.

Where Is Erlang Used Today?

If you think Erlang belongs in a museum next to floppy disks, think again. It’s alive, kicking, and powering some of the biggest telecom (and non-telecom) companies today.

Telecom Titans

- Ericsson (obviously—they made it)
- T-Mobile
- Verizon
- Nokia

Messaging Apps (Yes, even WhatsApp!)

WhatsApp uses Erlang to handle millions of concurrent connections with minimal hardware. Imagine trying to send memes to your friends during peak hours—Erlang makes sure your cat GIFs arrive on time.

FinTech and Banking

- Goldman Sachs
- Klarna

Imagine processing thousands of transactions simultaneously while keeping everything secure. Yep, Erlang does that too.

But… Isn’t Erlang Old?

Yes, Erlang has been around since the '80s. But guess what? So have C, Python, and Java—and nobody’s calling them dinosaurs just yet.

Age isn’t a disadvantage when it comes to maturity, reliability, and battle-tested performance. The fact that more modern languages struggle to replace Erlang in telecom speaks volumes.

Plus, Erlang isn’t living in the past. Elixir, a modern functional language that runs on the Erlang VM, is bringing fresh new developers into the ecosystem.

Why Haven’t More Companies Adopted Erlang?

Okay, so if Erlang is this amazing, why isn’t everyone and their grandma using it? A few reasons:

- Weird Syntax: If you’re used to Python or JavaScript, Erlang’s syntax might look a little… wonky. But once you get the hang of it, it’s not that bad.
- Niche Community: Compared to languages like Python, Erlang doesn’t have an army of developers, making hiring a bit tricky.
- Not for Everything: Erlang is perfect for telecom, messaging, and concurrent systems, but if you’re building a basic web app, you might be better off with something else.

The Verdict: Should You Learn Erlang?

If you’re a telecom engineer, working in real-time messaging, or building highly concurrent systems, yes, Erlang is still worth learning.

It offers:
✅ Rock-solid reliability
✅ Insane concurrency handling
✅ Fault tolerance that keeps systems running smoothly
✅ Live code updates without downtime

Is Erlang going anywhere? Nope. It may not be as trendy as Python or JavaScript, but it continues to power the world’s most demanding telecom systems quietly and efficiently.

So next time you make a call and it doesn’t drop? You probably have Erlang to thank.