SIP Trunking Upgrade Checklist: Network, SBC, QoS, and Porting Pitfalls

Avoid Costly SIP Trunking Surprises Before You Cut Over

Upgrading to SIP trunks should feel like a clean step forward, not a leap of faith. Done well, it gives you flexible calling, easier growth, and one simple way to connect offices, cloud apps, and remote staff. Done badly, it can mean dropped calls, poor audio, and long days trying to work out what went wrong.

Many Australian businesses plan SIP upgrades around spring and early planning cycles, when IT teams are mapping out projects for the year ahead. That timing makes sense, but it also means networks are often busy and change windows are tight. If you miss checks on network capacity, Session Border Controllers (SBCs), Quality of Service (QoS), or number porting, a simple cutover can suddenly become messy.

A good SIP trunking provider will guide you through the details and help you lower the risk. At NewVo, we see four big pillars for a smooth migration: network health, secure and well-designed SBCs, strong call quality controls, and well-planned number porting. This checklist walks through each one so you can head into cutover day with confidence.

Test Your Network Before SIP Traffic Hits

Before you move calls off traditional lines, you need to know if your network can carry voice without breaking a sweat. Voice is not as forgiving as email or web browsing. Small issues that no one notices today can be very obvious once every call runs over IP.

Start by checking how your bandwidth is used now and include the other sources of demand that will compete with voice during the day:

• Expected concurrent calls across the business

• Video meetings, screen sharing, and webinars

• Cloud apps like CRM and file storage

• Remote access from staff on VPN or similar tools

Look at busy times too, like end of quarter, end of day, and the lead-up to the holidays when teams are chasing deadlines, because these periods often expose capacity constraints that don’t show up in quieter weeks.

Next, run proper VoIP readiness testing. A simple speed test does not tell you how your network treats real-time voice, so aim to measure the indicators that directly affect call quality:

• Jitter

• Packet loss

• Latency

• MOS (Mean Opinion Score) from real call simulations

Then review what is happening inside your walls. Your LAN, Wi‑Fi and routers can introduce issues even if your internet link is strong, so check for the most common internal causes of voice instability:

• VLANs or separate segments for voice

• Duplex or speed mismatches on switch ports

• Old switches without QoS features

• Single points of failure on core links or access switches

Plan redundancy before you need it. That could include a second internet link, 4G or 5G backup, and a clear process if your primary SIP trunks or NBN service fail. Decide who makes the call to fail over, what systems are affected, and how you will let staff know.

Get Your SBC and Security Config Right From Day One

Your SBC is the traffic controller at the edge of your voice network. It is more than a security box: it also plays a core role in how calls are routed, translated and handled between platforms. In practice, it can:

• Route calls between different carriers and sites

• Normalise SIP signalling between your PBX and SIP trunks

• Bridge older PBXs with newer platforms like Microsoft Teams

• Help with codec negotiation and media handling

Security needs just as much thought as routing, because SIP is a common target for toll fraud and denial-of-service attacks. From day one, plan to:

• Use TLS for SIP signalling where possible and SRTP for media

• Limit access with IP allow lists and access control lists

• Apply geo-blocking so you only accept traffic from needed regions

• Use SIP-aware firewalls that understand VoIP traffic

Decide where your SBC lives, because the right placement depends on compliance requirements, operational preferences, and in-house capability. Options include:

• On-premises hardware in your comms room

• A virtual SBC in your data centre

• A cloud-hosted SBC managed by your SIP trunking provider

Your choice should fit your compliance needs, your preference on data staying within Australia, and your IT skills.

Document everything so you have consistency during rollout and clarity during troubleshooting. That documentation should cover:

• Standard dial plans and number formats

• Rules for how you handle mobile, local, national and international calls

• How emergency calls are routed and presented

• A rollback plan in case early cutover tests uncover issues

Lock in QoS so Voice Always Wins Over Netflix

If your network treats voice like any other traffic, it will suffer the moment someone starts a big download or streams video. QoS is how you make sure voice traffic gets a better seat.

Start by mapping where QoS needs to be set across the full path voice will take, because inconsistent configuration creates unpredictable results:

• Edge routers at each site

• Core and access switches

• Wi-Fi controllers and access points

• Any SD-WAN appliances

Classify and mark SIP and RTP traffic so the same rules apply from handset to core router. Make sure your QoS model is simple enough that your IT team can support it long term.

QoS cannot stop at your door, so talk with your SIP trunking providers and internet carriers about what they will honour once traffic leaves your network:

• What QoS markings they recognise

• How they treat real-time traffic on their network

• Any managed options that include monitoring and reporting

You also have choices on codecs, and it’s worth matching codec decisions to the reality of each link and user group. You might use G.711 where bandwidth is strong and audio quality is key, and consider G.729 or Opus where links are tight or you have many remote users. Different lines may need different profiles; for example, contact centre agents and executive staff often expect higher quality and more careful monitoring.

Finally, set up ongoing monitoring, not just one-off tests, so you can spot deteriorating performance before users complain. You want:

• Dashboards for jitter, latency and MOS

• Thresholds for when alerts should fire

• Simple reports your IT team can review in regular check-ins

Avoid Number Porting Delays and Downtime

Number porting sounds simple: move numbers from one carrier to another. In practice, it can be slow if the groundwork is not done properly.

Start with a full audit of your numbers so nothing critical is missed and no unexpected dependencies hold up the port:

• Geographic numbers across all sites

• 1300 and 1800 services

• Fax, EFTPOS, lift phones and alarm lines

• Any numbers tied to special services or legacy gear

Decide which services should move to SIP and which should stay on other technology for now, especially critical services like alarms.

Learn the porting rules and lead times in Australia. Different carriers have different forms and data fields, different treatment for complex services and ranges, and blackout dates around public holidays or planned network work.

Clean documentation prevents rejections. Make sure your:

• Letter of Authorisation matches the current carrier records

• Legal entity and trading names are correct

• Address and ABN are accurate

• Number ranges and service types match your invoice

Plan cutover so staff and customers barely notice anything happened. That often means:

• Using test numbers for early checks

• Staggering ports by site or number range

• Having call forwarding ready as a fallback

• Sharing clear internal comms so people know what is changing and when

Choose SIP Trunking Providers Who Back You up

Not all SIP trunking providers handle migrations the same way. Price matters, but support and experience often matter more on cutover day.

When you compare options, think about:

• Australian-based support that understands local carriers and regulations

• 24/7 incident response for outages outside normal hours

• SLAs that match your business risk

• Proven experience with your PBX or UC platform

Also check how well a provider fits your future plans, not just your current PBX. Ask about:

• Native or certified integration with Microsoft Teams

• Support for cloud UC and contact centre platforms

• The ability to scale channels quickly for seasonal peaks or new sites

Migration support is just as important, because even a good product can fail in deployment without the right process. Look for a provider that offers:

• Pre-cutover assessments of your network and configuration

• Joint testing windows with your IT team

• A pilot phase with a small group of users

• Training for your internal IT and service desk teams

Finally, confirm how they handle compliance and resilience:

• Data centres hosted onshore

• High-availability voice architecture across multiple locations

• Reliable emergency call handling

• Documented disaster recovery processes that you can align with your own

By working through this checklist with an experienced provider like NewVo, you can move to SIP trunking with clear eyes, clear steps and a clear plan to protect call quality and business continuity.

Upgrade Your Business Communications With Reliable SIP Trunking

If you are comparing SIP trunking providers, we can help you design a solution that fits your call volumes, locations and budget. At NewVo, we work with you to streamline your existing phone environment while improving call quality and resilience. Talk to our team today to map out the right approach for your organisation or simply contact us to get a tailored proposal.