SureTel
Business VoIP Trunking
SIP Trunking for Business Phone Systems
Connect your compatible PBX, PABX or call centre platform to business VoIP without replacing the phone system you already use.
SureTel SIP trunking gives businesses a practical way to add VoIP calling capacity, manage business numbers and support inbound or outbound calling through a compatible existing phone environment.
- Licensed SA ISP
- ICASA 0009/CECS/AUG/09
- Since 2010
- Trusted by hundreds of SA businesses
WHAT IS SIP TRUNKING?
Connect Your Existing PBX to Business VoIP
SIP trunking is a method of connecting a compatible PBX, PABX or call centre platform to VoIP calling over an IP network. It gives the phone system a route for making and receiving external calls without relying only on traditional telephone trunks.
For a business, SIP trunking can be useful when the current PBX still meets operational needs, but the company wants more flexible call capacity, better integration with VoIP services or a clearer path for number migration and future growth.
In plain English: Think of a SIP trunk as the voice connection between your existing phone system and the wider telephone network. Your PBX continues to manage internal extensions and call handling, while SIP trunking provides the external calling path.
SIP trunking connects a compatible existing PBX, PABX or call-centre platform to VoIP calling over an internet connection. Instead of replacing your entire phone system, SureTel can help you add the SIP channels, call routing and number-planning requirements needed for your current environment. Request SIP trunk pricing to assess compatibility, channel capacity, call usage and number-porting requirements.
- • SIP trunking for compatible existing PBX and PABX systems
- • Suitable for businesses, call centres and multi-branch environments
- • Add VoIP call capacity without necessarily replacing your current phone system
- • SIP channels are planned around simultaneous call requirements
- • Number porting support for eligible numbers
- • Works alongside SureTel VoIP, Cloud PBX, Onsite PBX and Hosted VICIdial where relevant
- • Requires compatibility, connectivity and configuration assessment before deployment
Choose the right voice solution
SIP Trunking, VoIP and Cloud PBX: What Is the Difference?
Choose SIP trunking when your existing phone system is compatible and still suits your business, but you need a modern route for external calling. Choose Cloud PBX when you want the phone system itself hosted and managed in the cloud.
| Solution | What it is | Best suited to | Primary destination |
|---|---|---|---|
| VoIP | Internet-based business calling. | Businesses that need modern calling services, call-rate guidance and flexible voice connectivity. | /services/voip → |
| SIP Trunking | A VoIP connection for a compatible existing PBX, PABX or call centre platform. | Businesses that want to retain their current phone system while adding VoIP call capacity. | /services/sip-trunking |
| Cloud PBX | A hosted business phone system with extensions, routing, voicemail and remote-working features. | Businesses that want to move away from onsite PBX equipment. | /services/cloud-pbx → |
| Onsite PBX | Locally installed phone-system hardware and software. | Businesses that require onsite control or a physical PBX environment. | /services/onsite-pbx → |
Who it fits
SIP Trunking May Be Suitable When You Already Have a Phone System
You have a compatible PBX or PABX
Keep your current phone system while replacing or supplementing traditional external voice trunks.
You operate a call centre
Add VoIP call capacity to a compatible dialler or call centre platform, subject to channel, connectivity and configuration requirements.
You have multiple branches
Support a more coordinated voice environment across locations where the PBX, routing and connectivity design allow.
You want to retain existing hardware
Extend the working life of an existing compatible PBX rather than replacing it immediately.
You need more simultaneous calls
Add channel capacity based on the number of concurrent external calls your business expects.
You need number-porting planning
Move eligible business numbers into a new voice arrangement without automatically changing the number your customers know.
You are not ready for Cloud PBX
Use SIP trunking as a practical transition path while retaining existing onsite equipment.
You need call-centre or outbound calling capacity
Plan SIP channels, routing and connectivity around call volumes, call patterns and platform requirements.
Problems this solves
Common Business Voice Problems SIP Trunking Can Help Address
Traditional voice trunks are costly or difficult to scale
SIP trunking can provide a more flexible VoIP-based external calling path for compatible PBX systems.
Your PBX still works, but the external voice setup is outdated
Keep the existing compatible PBX while updating how it connects to external voice services.
Your business needs more simultaneous call capacity
Plan SIP channels around expected concurrent inbound and outbound calls rather than relying on fixed traditional trunk capacity.
You are uncertain whether you need Cloud PBX or a new onsite PBX
SIP trunking can be a suitable middle path for businesses that want to modernise calling without immediately replacing their current PBX.
Your call centre needs a voice route for inbound or outbound activity
SIP trunking can form part of a properly designed call centre voice environment when paired with a compatible dialler, routing plan and suitable connectivity.
Business numbers are tied to your existing provider
Eligible numbers may be considered for porting through the applicable process, subject to number type, provider requirements and documentation.
Multiple sites use disconnected voice services
SIP trunking can support a more centralised voice design when branch connectivity, PBX architecture and routing requirements are properly planned.
You need a continuity or failover plan
SIP trunking can form part of a broader resilience design, but failover must be deliberately configured and tested. It is not automatic in every deployment.
Your PBX compatibility is unclear
SureTel can assess the PBX, dialler or phone environment before recommending trunking, channel capacity or an alternative solution.
SIP trunking depends on compatible equipment, a suitable internet connection, correct PBX configuration, call-capacity planning and testing. It does not automatically resolve poor local networking, unsupported PBX hardware or an inadequate continuity design.
Why businesses use SIP trunking
Why Businesses Use SIP Trunking
A practical way to modernise external calling when an existing compatible PBX still suits the business.
Keep a compatible PBX in service
Retain an existing phone system that still meets business requirements while modernising the external calling connection.
Add VoIP call capacity
Connect external business calling to an IP-based voice service instead of relying only on traditional trunks.
Plan capacity around real call demand
Size SIP channels according to expected simultaneous inbound and outbound calls.
Support call-centre environments
Use SIP trunking as part of a compatible inbound, outbound or blended call-centre voice setup.
Support number continuity
Plan eligible number porting so established business numbers can potentially move with the new voice arrangement.
Prepare for future change
Create a practical transition path toward Cloud PBX, new onsite PBX infrastructure or a more integrated business voice environment.
Support multi-branch voice requirements
Coordinate voice connectivity across multiple locations where the PBX and network design support the required routing model.
Use one provider for voice and connectivity planning
Combine SIP trunking with SureTel VoIP and business connectivity advice where appropriate.
Channel sizing
How Many SIP Channels Does Your Business Need?
A SIP channel is generally planned as one simultaneous external call. For example, if your business needs to make or receive up to 10 external calls at the same time, the starting requirement may be around 10 channels. Final sizing must also consider your PBX capacity, licensing, call patterns, connectivity, codecs, routing configuration and any call-centre requirements.
Small office
How many external calls are likely to happen at the busiest time?
Reception-led business
How many incoming calls can arrive while staff are also making outbound calls?
Sales team
How many agents may be calling customers simultaneously during peak periods?
Call centre
How many inbound, outbound or blended calls need to run at the same time?
Multi-branch business
Are call channels shared centrally, or does each branch require dedicated capacity?
Seasonal business
Do campaigns, month-end periods or promotions create temporary peaks in call volume?
Do not choose SIP channels only by counting employees. A business with 30 staff may need fewer than 30 simultaneous external call channels, while a call centre may need more channels than its normal office-user count suggests.
Service details
SIP Trunking Designed Around Your Existing Phone Environment
PBX and Platform Compatibility Review
SureTel reviews your current PBX, PABX, IP PBX, dialler or call-centre platform before confirming whether SIP trunking is suitable.
SIP Channels
Channels are planned around the number of simultaneous external calls your business needs to make or receive during busy periods.
Inbound and Outbound Calling
Use SIP trunking for incoming and outgoing business calls through the approved PBX or call-centre platform.
Number Porting
Where eligible, SureTel can help plan the migration of existing business numbers into the new SIP-trunking environment.
Call Routing
Plan how incoming calls route to extensions, queues, reception teams, branches, IVR menus or other approved destinations.
Failover and Continuity Planning
Discuss backup routes, alternate destinations, secondary connectivity or continuity requirements as part of the solution design. These measures must be specifically configured, tested and agreed.
Connectivity Requirements
SIP trunking depends on suitable business connectivity. The final design should consider bandwidth, latency, packet loss, concurrent calls, firewall and NAT behaviour, local network configuration and quality-of-service requirements where relevant.
Testing Before Go-Live
Complete call testing, routing checks, number validation and operational sign-off before production cutover.
Pricing
SIP Trunk Pricing Depends on Your Channels and Call Requirements
VoIP call rates from R0.30 per minute excl. VAT
- • SIP channel capacity quoted according to the number of simultaneous external calls your business needs
- • VoIP call rates from R0.30 per minute excluding VAT may apply where relevant
- • Per-second billing may apply depending on the selected service and call type
- • Minute bundles from R300 per month may be available where suitable for your usage profile
- • Number porting requirements and any associated costs are confirmed after eligibility and documentation are reviewed
- • PBX integration costs can be affected by compatibility, configuration, testing, routing and any required hardware or professional services
- • Call-centre pricing depends on the dialler, channels, users, traffic profile, reporting and connectivity requirements
- • Backup connectivity, alternate routing and resilience requirements are quoted according to the agreed design
SureTel does not publish a one-size-fits-all monthly SIP channel price because requirements vary by PBX compatibility, channel capacity, call volumes, destinations, number-porting requirements, routing complexity, connectivity and support needs.
All prices are shown excluding VAT unless stated otherwise.
See the full tiered pricing
Detailed per-extension tiers, call-recording add-ons, minute bundles and call rates live on the dedicated pricing page.
Phone-system approaches
Which Business Phone-System Approach Is Right for You?
| Consideration | SIP Trunking | Cloud PBX | Onsite PBX |
|---|---|---|---|
| Core phone system | Keeps a compatible existing PBX or PABX in place. | Uses a hosted phone system managed in the cloud. | Uses PBX equipment installed at your premises. |
| Best use case | You have a working compatible PBX and need VoIP call capacity. | You want to replace or modernise the phone system itself. | You need locally installed equipment or specific onsite control. |
| Primary value | Modernise external calling without replacing the PBX immediately. | Hosted extensions, routing, remote working and managed phone features. | Local equipment control and custom onsite configurations. |
| Hardware dependency | Retains existing PBX hardware. | Reduces dependency on core PBX hardware at the customer site. | Requires local PBX hardware and supporting infrastructure. |
| Remote and multi-branch use | Depends on existing PBX capability, network design and configuration. | Often suitable for remote and multi-branch users when configured appropriately. | May require additional infrastructure or remote-access planning. |
| Scalability | Add call capacity by planning SIP channels and compatible PBX capacity. | Add or adjust users and extensions within the hosted platform. | Scaling may depend on hardware capacity, licences and onsite changes. |
| When to choose it | Your current PBX still suits the business. | You want a flexible hosted business phone system. | You require an onsite phone-system environment. |
Call centres
SIP Trunking for Inbound and Outbound Call Centre Environments
SIP trunking can form part of a call-centre voice environment where a compatible dialler or PBX platform needs external inbound and outbound calling capacity. Channel sizing, connectivity, CLI requirements, routing, call recording, reporting, carrier rules and continuity planning should be assessed before deployment.
Relationship to Hosted VICIdial: Hosted VICIdial is a complete hosted call-centre dialler platform. SIP trunking is the voice connectivity method that may support compatible existing call-centre systems.
Inbound customer-service teams
Suitable call-centre scenario.
Outbound sales teams
Suitable call-centre scenario.
Blended inbound and outbound operations
Suitable call-centre scenario.
Predictive or progressive dialling environments
Suitable call-centre scenario.
Multi-site call centres
Suitable call-centre scenario.
Call centres moving away from traditional voice trunks
Suitable call-centre scenario.
Businesses using compatible self-hosted or hosted call-centre platforms
Suitable call-centre scenario.
Setup process
How SureTel Plans a SIP Trunking Deployment
Tell us about your current system
Share your PBX, PABX, IP PBX or call-centre platform, number requirements, locations, call volume and current connectivity.
Compatibility and requirements review
SureTel assesses whether the existing platform and network environment are suitable for SIP trunking.
Channel and call-plan recommendation
Define the expected number of simultaneous calls, inbound and outbound requirements, routing and usage profile.
Number and porting plan
Review existing business numbers, eligibility, documentation and the intended cutover approach.
Connectivity and continuity planning
Confirm the primary connection, network requirements and any agreed backup or failover measures.
Configuration and testing
Configure trunking, call routing, PBX settings and test inbound, outbound and operational call flows.
Go-live and monitoring
Move into production once testing is complete, with service support according to the selected agreement.
Deployment timing depends on compatibility, configuration complexity, number-porting requirements, connectivity readiness, testing and the agreed implementation scope.
Why SureTel
Why Choose SureTel for SIP Trunking?
Licensed South African ISP
SureTel provides business communications and connectivity services within the South African telecommunications environment.
Operating since 2010
Practical experience supporting business voice, connectivity and communication requirements.
PBX-first assessment
SureTel reviews the current phone-system environment before recommending SIP trunking, Cloud PBX or another solution.
Voice and connectivity planning together
Consider PBX requirements, voice capacity, internet connectivity and backup planning as part of one solution.
Number-porting guidance
Support for evaluating eligible number-porting requirements, documentation and cutover planning.
Business-focused implementation
Solutions planned around users, branches, call volumes, routing needs and operational priorities.
Support hours, escalation arrangements and service levels depend on the selected service and agreement. Do not imply universal 24/7 support, automatic failover or fixed SLA commitments.
FAQ
SIP Trunking FAQs
What is SIP trunking?
SIP trunking connects a compatible PBX, PABX, IP PBX or call-centre platform to VoIP calling over an internet connection. It provides the external voice route for making and receiving business calls while your existing phone system continues to manage extensions and internal call handling.
Who needs SIP trunking?
SIP trunking may suit businesses that already have a compatible PBX, PABX or call-centre platform and want to add VoIP calling capacity without immediately replacing the existing system. It can be suitable for offices, multi-branch businesses, professional services firms and call centres.
How is SIP trunking different from VoIP?
VoIP is the broader method of making calls over an IP network. SIP trunking is a specific way to connect a compatible existing PBX or call-centre platform to VoIP calling. A business may use VoIP without SIP trunking, but SIP trunking is commonly used where an existing PBX needs an external VoIP connection.
How is SIP trunking different from Cloud PBX?
SIP trunking keeps your current compatible PBX in place and connects it to VoIP calling. Cloud PBX is a hosted phone system that replaces or reduces reliance on onsite PBX equipment. SIP trunking may suit businesses that want to retain their existing PBX, while Cloud PBX may suit businesses that want a more flexible hosted phone system.
Can SIP trunking work with my existing PBX?
It may, provided that the PBX or PABX is compatible and the network environment is suitable. SureTel will assess the phone system, software version, supported SIP configuration, call capacity, firewall and connectivity requirements before confirming a solution.
How many SIP channels does my business need?
A SIP channel is generally planned as one simultaneous external call. The right number depends on your busiest calling periods, the number of incoming and outgoing calls that may happen at once, your PBX capacity, user behaviour, call-centre activity and available connectivity. SureTel can recommend an appropriate starting point after reviewing your requirements.
Can I port my existing business numbers to a SIP trunk?
Eligible business numbers may be ported through the applicable South African porting process. Porting depends on the number type, current provider, required documentation, technical readiness and successful completion of the process. SureTel can assess your requirements before the migration is planned.
Is SIP trunking suitable for call centres?
Yes, SIP trunking can be suitable for compatible call-centre systems that require inbound, outbound or blended calling capacity. The solution must be planned around concurrent calls, dialler or PBX compatibility, call-routing rules, connectivity, CLI requirements and continuity considerations.
Does SIP trunking include automatic failover?
Not automatically. SIP trunking can form part of a continuity design, but failover depends on the specific configuration, routing rules, connectivity options, backup links, PBX capability and testing plan agreed for your business.
Does SureTel provide SIP trunking across South Africa?
SureTel can assess SIP trunking requirements for businesses across South Africa. Final availability and deployment depend on your existing platform, voice requirements, connectivity, number-porting needs and technical feasibility.
Get started
Keep Your PBX. Modernise Your Business Calling.
- Licensed SA ISP
- ICASA 0009/CECS/AUG/09
- Since 2010
- Trusted by hundreds of SA businesses
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All prices are shown excluding VAT unless stated otherwise.