Scaling a telecom application is not simply adding more servers. Rather, it makes sure every layer of your stack works seamlessly be it routing, media processing, failover, and traffic distribution. Making sure the system is designed to handle growth without breaking down. Kamailio and FreeSWITCH together gives you exactly that kind of architecture.
Have a look at how scaling actually works when you build on this combination.
Separating Signalling and Media Is the First Step
First, to make scaling easier, stop treating signalling and media as a single unit. In this architecture, Kamailio handles all SIP signalling at the front end; on the other hand, FreeSWITCH instances manage media processing behind it.
Basically, this separation can scale each layer independently. So, if you’re receiving more call setup requests, you tune and scale the signaling layer. If you’re processing more concurrent audio streams, you add media nodes. You’re not forced to scale everything together every time one layer hits a limit.
How Load Distribution Works Across the Stack?
Distributing Calls Across FreeSWITCH Nodes.
Kamailio’s dispatcher module looks how incoming calls get dispersed across multiple FreeSWITCH instances running behind it. You can then tune this distribution using different strategies.
Like,
- Round-robin : Spreads calls evenly across all active nodes It operated very well when call durations are roughly consistent.
- Least-loaded Routing: It routes each new call to whichever node is currently handling the fewest active calls. It works well for workloads where call durations vary.
- Weighted distribution : It distributes more traffic to higher-capacity nodes. It runs when your infrastructure is not uniform.
Horizontal Scaling at the Media Layer
When the traffic is at peak, you extend FreeSWITCH nodes to the pool. Kamailio picks them up and starts to include them in the distribution logic.
Scaling horizontally at the media layer is far more practical than trying to push a signal server beyond its limits. Each node handles a portion of concurrent calls, and the total capacity of your platform grows proportionally.
Handles Failures Without Dropping Calls!
How?
Automatic Node Health Monitoring
You would love to know that Kamailio continuously monitors the operation of each FreeSWITCH node via SIP OPTIONS pinging.
Suppose, a node stops responding, Kamailio considers it unavailable and stops routing new calls to it. Ultimately, it reroutes the existing traffic to healthy nodes. This happens on automation without manual intervention.
Call State Management Across Nodes.
One area that needs careful planning at scale is the call state. Each FreeSWITCH instance holds active call state in memory. For example, if a node goes down mid-call, that state is gone unless you’ve built external state management into your setup.
There are some common approaches that includes using a shared database or an external cache like Redis to store dialog state, this make recovery possible in every way, even when a node fails unexpectedly.
Redundant Deployment
Kamailio itself should not be a single point of failure. In production deployments, you run multiple Kamailio instances with a shared IP or a floating IP managed by keepalived. If the active Kamailio node goes down, the standby takes over with no impact on active calls.
Scaling for Specific Telecom Use Cases:
High-Concurrency Call Centres
Call center platforms manage a large number of calls simultaneously, often with various techniques such as queuing, recording and agent routing on top. The Kamailio-FreeSWITCH architecture handles this by distributing calls across dedicated FreeSWITCH nodes, some for queuing logic, some for active call processing. On the other side, Kamailio manages which calls go where based on real-time load.
Multi-Tenant VoIP Platforms
Kamailio manages tenant-level routing logic, directing each tenant’s traffic to their allocated FreeSWITCH resources for platforms serving multiple businesses or clients on shared infrastructure. Keeping tenants isolated at the signalling level while still running on a shared backend. This way, it makes the platform operationally efficient to manage.
WebRTC and SIP Interoperability at Scale
Scaling becomes even more complex when you need to support both browser-based WebRTC clients and traditional SIP devices on the same platform. Kamailio handles the SIP signaling for both, whereas FreeSWITCH manages protocol conversion and media, being a bridge between WebRTC and SIP endpoints. As WebRTC traffic grows, you scale the FreeSWITCH nodes handling that conversion workload independently from nodes serving standard SIP calls.
Security and Performance as You Scale
As you scale, your attack surface grows too. More traffic means more exposure to SIP floors, brute-force registration attempts, and toll fraud. At the Kamailio layer, rate limiting, IP whitelisting, and TLS for encrypted signalling are standard configurations that should be in place before you scale, not after. FreeSWITCH nodes should not be directly exposed to the public internet; all traffic should pass through Kamailio first.
On the performance side, tuning matters. When there is increase in call volume, things such as SIP timer configurations, database connection pooling, and RTP port range allocation need to be revisited. They need to be adjusted as your platform grows.
Onboard a Kamailio Developer Just in 48 Hours.
Getting this architecture right in production demands great experience. So, if your team is building this for the first time, it definitely makes sense to hire a Kamailio developer or work with a team that offers Kamailio Development Services. At Vindaloo Softtech, we have a solution to your every problem.
Whether you are seeking routing script configuration, failover logic, or security strengthening, we do it all. What’s More! You can also hire a VoIP developer at Vindaloo Softtech for custom integrations like billing, analytics or CRM connectivity.
Explore our flexible Hiring models and benefits of onboarding a Kamailio developer at Vindaloo Softtech.
Let’s talk, how we can make your journey easier and smarter.
