Photon builds Spectrum, the messaging API that lets your product text customers on iMessage, WhatsApp, Telegram, Discord, Slack, and SMS. Built for AI agents first: enterprise deployments run 1M+ messages per agent per day on Spectrum, and dozens of YC startups use it in production. Business plan ($250/line/mo — 50% off with the deals): dedicated iMessage lines with unlimited daily messages, full direct + group messaging API, iOS 26 features (polls, location sharing, chat backgrounds), cold outreach support, bring-your-own iMessage mini apps, unlimited users, and a dedicated Slack & Discord support channel. The lowest throttling on the platform, dedicated lines you own outright, custom WhatsApp and voice packages, and enterprise-grade SLAs. This is the tier running 1M+ messages per agent per day for clients like Rho, Vercel, and Ditto.