What is SIP Trunking?
SIP trunking connects your phone system to the public telephone network over the internet, replacing physical phone lines (ISDN/PSTN) with virtual ones. Each trunk carries multiple simultaneous calls and scales up or down instantly without new hardware or line installations.
Why SIP Trunking matters for Australian businesses
Your network infrastructure is the foundation of your entire IT environment. Poorly designed or outdated infrastructure leads to slow performance, security vulnerabilities, and costly downtime. As businesses adopt hybrid work, cloud services, and IoT devices, a modern, well-managed network is more important than ever.
For small and medium businesses in particular, SIP trunking can make a real difference in maintaining a secure, efficient, and resilient IT environment. Whether you are reviewing your current setup or planning improvements, understanding the role of SIP trunking in your broader IT strategy will help you have more informed conversations with your IT provider and make better decisions for your business.
Related terms
VoIP • Hosted PBX • NBN
How All IT Services can help
At All IT Services, we help businesses across Sydney, Brisbane, Melbourne, and regional NSW implement and manage SIP trunking as part of our comprehensive internet and telephony services. If you have questions about how this fits into your IT strategy, contact our team for a no-obligation consultation.
Frequently Asked Questions
What is SIP trunking?
SIP trunking delivers your phone lines virtually over the internet, connecting your PBX to the telephone network without physical copper or ISDN circuits.
How many calls can a SIP trunk handle?
As many channels as you subscribe to — capacity is licensed, not wired, so adding lines for seasonal peaks takes minutes instead of weeks.
What happened to ISDN in Australia?
ISDN was decommissioned as the NBN rolled out, making SIP trunking the standard way business phone systems now reach the outside world.