VoIP System Setup

I run an Australian after-hours support service and need a seasoned VoIP engineer to design, configure and fully automate our new cloud telephony environment.

What I need the system to do
Our operation supports 30+ client organisations, each with its own Australian DID. After business hours every call must be routed automatically to our overseas team, so rock-solid automated call forwarding and routing is the number-one priority. The platform also has to cover call recording, voicemail, SMS escalation through ClickSend, real-time activity reporting and the flexibility to scale as we add new clients.

Tech landscape
I am open to any robust solution—3CX, Twilio, a SIP-based cloud PBX or a hybrid you recommend—provided it delivers reliability, security and straightforward remote management.

Your proposal
Please show relevant past work that demonstrates you have built similar multi-tenant, after-hours call-centre environments. In the same submission outline:
• your recommended architecture and why you chose it
• an estimate of setup costs versus ongoing per-month costs (licensing, trunks, SMS, etc.)
• a clear implementation timeline with key milestones
• details of the post-launch support package you can offer on a fixed-price basis

Acceptance
The engagement is complete once the system is live, tested end-to-end, and my team can seamlessly handle, record and track calls while automated SMS alerts fire through ClickSend without fail.

If this sounds like a build you can deliver, I look forward to reviewing your approach and past projects.