Bulk SMS Scheduler Development

I need a reliable bulk-SMS platform that lets me compose a message once, load thousands of numbers, and schedule exactly when every batch leaves the gateway. The core requirement is scheduling—think calendar-style controls or cron-like flexibility—so campaigns can be created days in advance and fire automatically, even if I’m logged out.

Key functions I expect:
• Upload or paste recipient lists (CSV, TXT, or manual entry).
• Create, edit, and delete campaigns with a clear “send at” field.
• Real-time status dashboard showing queued, sent, failed, and delivered counts.
• Simple REST or HTTP API so my existing CRM can trigger sends.
• Basic sender ID or shortcode handling in markets that allow it.

I’m open on stack—Laravel, Node, Python, or Go are all fine as long as the UI stays clean and performance scales. If you already work with Twilio, Vonage, Plivo, or any SMPP gateway, mention that in your proposal. Voice broadcasting isn’t in scope for this phase, but I’d like the architecture to be modular enough to bolt it on later.

Send me a detailed project proposal outlining:
• Your recommended tech stack and why
• Key milestones with timelines
• Any assumptions (e.g., gateway costs, server specs)
• A brief plan for testing delivery rates and failover

I’ll review proposals that cover those points thoroughly and choose the freelancer whose roadmap feels most robust and transparent.