If your business is on TM MLS (Telekom Malaysia Multi Line SIP), an older TM PRI line, or an ageing on-premise PBX, you've probably been told it's time to modernise. Moving to managed cloud voice is the natural next step — you keep your Telekom Malaysia numbers, drop the box in your server room, and gain a phone system your team can use from anywhere. This guide explains what TM MLS is, why businesses migrate to cloud, and exactly how the move works without disrupting your calls.
What is TM MLS (Multi Line SIP)?
TM MLS is Telekom Malaysia's SIP trunking service — it carries several concurrent voice channels over an internet connection instead of traditional copper or PRI/E1 lines. TM introduced MLS to migrate customers off legacy PRI and analogue services; because it rides the same infrastructure as Unifi, new sites don't need separate voice cabling. In short, MLS is the lines. It still needs a phone system (a PBX) behind it to actually route, answer and manage calls.
Why businesses move off legacy / TM MLS to cloud
- The PBX hardware is ageing — out of warranty, hard to get parts, expensive to fix.
- Staff work from anywhere now — a box tied to the office can't follow them home or on the road.
- Adding or moving extensions is slow — every change needs a technician.
- No modern features — voicemail-to-email, mobile apps, self-service routing, recording and reporting.
- Single point of failure — one box in one office; if it dies, the phones die.
Moving to a managed cloud PBX keeps your TM numbers while solving all of the above — and the system is hosted, monitored and supported for you.
Your migration paths
There are two clean ways to migrate, and you can mix them:
- Keep your TM MLS trunk, add a cloud PBX (BYOC). Point your existing Telekom Malaysia MLS trunk at the cloud phone system. Same lines and numbers, modern system behind them. Lowest-friction if your MLS contract is current.
- Full cloud. Port your numbers to the provider's carrier and run everything in the cloud. Simplest long-term; useful if you want to consolidate carriers or add international numbers.
Connecting a legacy PBX (if you're keeping it for now)
If you're not ready to retire an old TDM PBX, it can still reach SIP through a VoIP/SIP gateway that converts E1/analogue signalling to SIP, with a softswitch (such as FreeSWITCH) handling header manipulation and routing between the old system and the carrier. This is a useful bridge — but for most businesses the better end-state is to skip the gateway and move the phone system itself to the cloud.
Keeping your numbers
The number question is the most common worry, and the answer is simple: you keep them. Either your TM MLS trunk (with its numbers) is pointed at the cloud PBX, or the numbers are ported to the new carrier. Customers keep dialling exactly what they always have.
BYO trunk vs hosted numbers
| Bring your TM MLS trunk (BYOC) | Hosted numbers | |
|---|---|---|
| Numbers | Keep existing TM numbers, no port | Port existing or get new local/international |
| Carrier | Calls ride your TM lines | Calls ride the provider's carrier |
| Best when | MLS contract current; minimal change | Consolidating carriers; new numbers needed |
The migration steps
- Audit — list your numbers, lines (MLS/PRI), extensions, call flows and anything you must keep.
- Design — choose BYOC vs hosted; map extensions, IVR, ring groups and routing in the cloud PBX.
- Build & test — recreate everything in parallel; test on a few extensions and a test number.
- Cutover — point the trunk / port the numbers (often after hours), with the old line as fallback.
- Optimise — tidy routing, add mobile apps, enable recording/reporting, decommission old hardware.
With a managed provider, the build, test and cutover are done for you, including onboarding and migration from your current PBX.