AC-1 defines Chromatic Telephony, the first communication protocol in which presence, tone, and intent are transmitted through chromatic states rather than symbolic signals. Building on AP₁/AP₂ (Chromatic Operators & Chromatic Reasoning), CIL-1 (Chromatic Internet Layer), CIL-1.5 (Color Interpretation Layer), and CE-1 (Color Economics), AC-1 formalizes telephony as an ambient, state-driven field interaction. Chromatic Telephony replaces caller IDs, ringtones, icons, and metadata with direct color-encoded presence fields. A call appears as a Chromatic Presence Field (CPF), defined by chromatic state (C), temporal modulation (Δt), and resonance (Rf). Meaning arrives before language: color expresses intention, emotional tone, urgency, relational context, and trust long before words appear. Through reversible color↔language mapping (via CIL-1.5), AC-1 enables seamless transitions between presence, messaging, and speech. Telephony becomes cognitively lighter, emotionally richer, and thermodynamically efficient, reducing ΔR accumulation and restoring warmth to communication. AC-1 establishes the canonical laws of presence-first telephony and positions chromatic interaction as the default communication substrate of the Ambient Internet.