SIP Trunking Ireland: Provider Guide, Pricing & Setup

If your business is still on ISDN or paying over the odds for phone lines, SIP trunking is the upgrade you’ve been putting off. Ireland’s PSTN and ISDN networks are being phased out, and SIP is the replacement — delivering the same (or better) call quality at a fraction of the cost.

This guide covers everything Irish businesses need to know about SIP trunking: what it is, how it works, what it costs, and how to switch.

What Is SIP Trunking?

A SIP trunk is a virtual phone line that connects your phone system to the public phone network over the internet. Instead of physical copper lines running into your building, calls travel over your existing broadband connection.

SIP stands for Session Initiation Protocol — the standard technology that makes VoIP calls work. A “trunk” is the connection between your PBX (phone system) and the outside world.

For a deeper technical explanation, see our guide: What Is SIP Trunking?

In simple terms: SIP trunking replaces your old phone lines with internet-based ones. Same calls, same phone numbers, lower cost, more flexibility.

Why Irish Businesses Are Switching to SIP

1. ISDN Switch-Off

Eir and other Irish telecoms providers are decommissioning the ISDN network. If you’re still on ISDN, you’ll need to move to SIP or a hosted VoIP service regardless. Better to do it on your terms than be forced.

2. Cost Savings

SIP trunking typically cuts phone costs by 40-60% compared to ISDN:

A business with 10 ISDN channels paying €350/month in line rental alone could drop to €100-150 with SIP trunking — before you even count the per-minute savings.

3. Flexibility

• Add or remove channels instantly — no waiting for engineers to install physical lines
• Number portability — keep your existing numbers (01, 021, 061, 091, etc.)
• Geographic freedom — get Dublin 01 numbers for your Cork office, or any area code anywhere
• International numbers — get UK, US, or any country numbers for local presence

4. Business Continuity

• If your office loses power or internet, calls can failover to mobiles or another location
• No physical lines to cut or damage
• Disaster recovery is built-in

How SIP Trunking Works in Ireland

Your Phone System (3CX, Yeastar, etc.)
         ↕ (SIP over internet)
   SIP Trunk Provider (ITelecoms)
         ↕ (interconnects)
    Irish & International Phone Networks
         ↕
  Customers calling you / you calling them

1. Your phone system (3CX, Yeastar, Asterisk, FreePBX, etc.) connects to your SIP trunk provider over the internet
2. When someone calls your number, the SIP provider routes the call to your phone system
3. When you make a call, your phone system sends it to the SIP provider, who routes it to the destination
4. All of this happens over your existing broadband — no additional hardware or lines needed

What You Need

• Business broadband — minimum 100kbps per simultaneous call. Standard Irish business broadband (100Mbps+) handles 50+ calls easily
• A phone system — any SIP-compatible PBX:
  • 3CX — our recommended platform
  • Yeastar — excellent alternative
  • FreePBX, Asterisk, Avaya, Cisco — all work with SIP
• SIP trunk account — from a provider like ITelecoms
• Phones (optional) — desk phones, softphones, or just mobile/desktop apps

Number Porting in Ireland

You can keep your existing phone numbers when switching to SIP. Number porting is regulated by ComReg and typically takes 5-10 working days.

How it works:

1. You sign a porting authorisation with your new SIP provider
2. Your new provider submits the porting request to your current provider
3. On the porting date, your numbers switch over — usually overnight
4. Your service continues uninterrupted

Numbers you can port:

• Geographic numbers (01, 021, 061, 091, etc.) ✓
• 1800/1850/1890 numbers ✓
• Mobile numbers ✓ (though these typically stay with the mobile provider)

Important: Don’t cancel your existing phone lines before porting completes. The old provider needs the active lines to process the port.

SIP Trunk Configuration

Once you have your SIP trunk credentials, connecting to your phone system takes about 15 minutes:

3CX Setup

1. Log into 3CX Management Console
2. Go to SIP Trunks → Add SIP Trunk
3. Enter your provider credentials (server, username, password)
4. Add your phone numbers as DIDs
5. Set inbound routing rules
6. Test with a call

For a full walkthrough: How to Set Up a 3CX Phone System

Yeastar Setup

1. Log into Yeastar Management Portal
2. Go to Trunks → Add VoIP Trunk
3. Select SIP (Register-based)
4. Enter credentials
5. Create inbound routes
6. Test

Other PBX Systems

Most PBX systems follow the same pattern — add a SIP trunk with the provider’s server address and credentials. ITelecoms provides setup guides for all major platforms.

Choosing a SIP Provider in Ireland

What to look for:

• Irish presence — a provider who understands Irish telecoms, number ranges, and regulations
• Number porting experience — they should handle the porting process for you
• PBX compatibility — confirm they work with your phone system (3CX, Yeastar, etc.)
• Reliability — redundant infrastructure, SLA guarantees
• Support — Irish-based support, not a generic call centre
• Transparent pricing — no hidden fees, fair per-minute rates

ITelecoms SIP Trunking

• SIP trunks compatible with all major PBX platforms
• Number porting handled end-to-end
• Competitive call rates for Irish, UK, and international calls
• Irish-based support
• Paired with 3CX and Yeastar deployments for a complete solution

SIP Trunking + Microsoft Teams

Many Irish businesses use Microsoft Teams for collaboration. If you want to make and receive external phone calls from within Teams — calling landlines, mobiles, and international numbers — you need SIP trunking via Microsoft Teams Direct Routing.

Direct Routing connects your SIP trunks to Teams, giving your team full PSTN calling without leaving the Teams interface. This is significantly cheaper than Microsoft’s own Calling Plans, and you keep control of your numbers and routing.

Frequently Asked Questions

How many simultaneous calls can SIP handle?

As many as your bandwidth and trunk allow. Each call uses about 100kbps. A 100Mbps connection can theoretically handle hundreds of calls. In practice, SIP trunks are sold in channels — start with as many channels as you have current ISDN channels and adjust based on usage.

What happens if my internet goes down?

With proper failover configuration, calls can redirect to mobiles, another office, or voicemail. This is actually an advantage over ISDN — ISDN has no built-in failover.

Is call quality as good as ISDN?

On a decent broadband connection, yes — often better. SIP supports HD voice (wideband audio), which sounds noticeably better than standard ISDN audio. Quality depends on your internet connection, so prioritise voice traffic with QoS settings on your router.

Can I keep my 01/021/061 numbers?

Yes. All geographic numbers in Ireland can be ported to a SIP provider. The process takes 5-10 working days.

Do I need to change my phones?

If you have SIP-compatible IP phones (Yealink, Fanvil, Grandstream, Poly, etc.), no. If you have old analogue phones, you’ll need either new IP phones or an ATA (Analogue Telephone Adapter) to connect them.

What about emergency calls (999/112)?

SIP providers in Ireland are required to support emergency calling. Your registered address is provided to emergency services when you dial 999 or 112. Make sure your SIP provider has your correct address on file.

Ready to switch to SIP trunking? ITelecoms handles the entire process — from number porting to phone system configuration. Get in touch for a quote.