Keep the PBX hardware you already own and paid for - just replace the expensive copper phone lines behind it.
If your business already has a PBX or phone system you’re happy with, SIP trunking replaces the physical phone lines feeding it with a set of internet-based voice channels instead. There’s no need to rip out working hardware just to stop paying for legacy copper lines.
SIP trunks scale up and down with actual call volume, which matters most for businesses with seasonal spikes or a call centre-style setup, since you’re not stuck paying for fixed physical lines that sit idle most of the year.
Most modern PBX systems support SIP trunking natively or with a small gateway device. We'll check compatibility with your specific hardware before quoting.
Generally yes for call volume and line rental, since you're not paying for fixed physical copper infrastructure - the exact saving depends on your current plan and call patterns.
Yes, existing numbers can usually be ported across - see our Number Porting page for how that process works.