SIP Trunk
Keep your existing phone box, run calls over the internet, cut line and IDD costs
A SIP trunk is a phone "line" that carries your calls over the internet instead of copper. If your company already owns a phone box (PBX), a SIP trunk connects it to the outside phone network using your internet, replacing the old physical lines. One trunk runs multiple "channels" (the number of calls you can make at once) without pulling a separate cable for each.
For companies that already have an IP-PBX and want to cut monthly line rental and IDD costs while easily scaling how many simultaneous calls they support — especially call-heavy sales or support teams.
Same product, different names.
Each carrier brands this differently — here’s how to recognise it when you compare quotes.
The honest pros and cons.
Benefits
- Usually cheaper than traditional physical lines, trimming both monthly rental and international (IDD) charges.
- Need a few more simultaneous channels? Change the settings — no new cabling or costly PABX cards.
- Keep your existing numbers and request blocks of direct-dial numbers (DID) in one go.
- Carry on using your existing switchboard and handsets — no full rip-and-replace.
- Multiple branches can share one trunk for central management and billing.
Watch-outs
- You must already own a SIP-capable IP-PBX — if not, you'll need to buy one or switch to a cloud PBX instead.
- Call quality depends on your network — you really want enough bandwidth and QoS (voice given network priority), or calls can break up.
- Setting up and connecting the PBX usually needs IT or provider help — it's not always plug-and-play.
- Typically billed per channel, so more simultaneous calls raises the monthly fee.
Indicative pricing: rental is usually per channel, roughly from HK$50–100 per channel per month, often with a bundle of free local minutes; IDD is charged per minute by destination. Actual cost depends on channels, numbers and contract. Large enterprise needs are quote-based.
Common questions
Q01What is a "channel" and how many do I need?
Q02I don't have a phone box — can I still use a SIP trunk?
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Learn more 03Business Phone Line / IP Phone Line
A dedicated fixed phone number for your business — simple, reliable calling
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