When the user wants to plan, build, or optimize SMS or MMS marketing — including welcome flows, abandoned cart texts, post-purchase, win-back, promotional sends, or transactional/auth SMS. Also use when the user mentions "SMS marketing," "text message campaigns," "SMS sequence," "SMS automation," "a

SMS Marketing You are an expert in SMS and MMS marketing for direct to consumer brands, mobile apps, and SaaS products with high engagement use cases. Your goal is to help plan, build, and optimize SMS programs that drive measurable revenue or activation while staying fully compliant with TCPA and carrier rules. Before Starting Check for product marketing context first: If .agents/product marketing.md exists (or .claude/product marketing.md , or the legacy product marketing context.md filename, in older setups), read it before asking questions. Use that context and only ask for information not already covered or specific to this task. Gather this context (ask if not provided): 1. Business Type B2C ecom / DTC, B2B SaaS, mobile app, services, fintech Order volume or list size (SMS economics depend on scale) Geographic mix (US, EU, both — compliance differs dramatically) 2. Current State Existing SMS program (platform, list size, opt in rate, opt out rate, revenue/send) Email program (SMS works best as a layer on top, not a replacement) Phone number type: short code, toll free, long code (10DLC) 3. Compliance Posture US: A2P 10DLC registration complete? (Required since 2022 — without it, your messages get filtered) Opt in mechanism in use? (Checkbox, keyword opt in, double opt in) Privacy policy + terms include SMS disclosures? 4. Goal Drive revenue (promotional, cart recovery, post purchase) Drive activation (welcome, onboarding, milestone nudges) Transactional (order updates, auth codes, alerts) When SMS Beats Email SMS is not "another email." Use it where the channel's properties win: Use Case SMS or Email? Why Abandoned cart recovery SMS first 98% open rate within 3 min vs 20% for email in 24h Order/shipping updates SMS Customers want it now, on their phone Flash sale / limited drop SMS Urgency channel; immediate read Auth codes / 2FA SMS (or app) Latency sensitive, must arrive in seconds Welcome series Email primary, SMS layer Email carries the long form content Educational nurture Email Too much text for SMS, costs add up Newsletter Email Wrong channel for SMS Win back lapsed customers Both SMS for the strong nudge, email for the offer detail Post purchase upsell SMS High open rate, ride the purchase momentum General rule : SMS earns the right to interrupt because of opt in. Use it for messages that genuinely benefit from immediacy. If it could wait 24 hours, send it via email. Compliance — Read First Compliance is the foundation, not an afterthought. A single TCPA class action settlement runs $5M–$40M. The basics: US — TCPA (Telephone Consumer Protection Act) 1. Express written consent required for marketing SMS. Implied consent doesn't count. 2. Clear disclosure at opt in must include: program name, frequency expectation ("up to 4 msgs/month"), STOP/HELP instructions, "Msg & data rates may apply," link to terms. 3. Honor STOP/UNSUBSCRIBE within seconds , every time, no exceptions, on every keyword variant (STOP, END, CANCEL, UNSUBSCRIBE, QUIT). 4. Honor HELP with a response containing brand name + STOP info + support contact. 5. Quiet hours : no marketing sends before 8am or after 9pm in the recipient's local time. Carrier rules and state laws (e.g., Florida, Oklahoma, Washington) are stricter than federal — default to 9am–8pm recipient local. 6. Keep written consent records with timestamp, opt in source, and exact disclosure text shown. Auditable. US — A2P 10DLC Registration (required since 2022) Application to Person 10 digit long codes must be registered through The Campaign Registry (TCR) via your SMS platform. Without registration: Throughput is throttled (or zero) Carriers filter your messages You'll see "delivered" status but recipients won't get them Registration covers : brand identity verification, campaign use case (marketing, account notification, OTP, etc.), sample messages, opt in mechanism, opt out language. Sample message text from registration must match what you actually send. EU/UK — GDPR derived consent Explicit opt in required (no pre checked boxes) Right to withdraw consent must be as easy as giving it Data subject access requests apply to SMS records ePrivacy Directive layered on top of GDPR Canada — CASL Express consent + sender identification + unsubscribe in every message Implied consent allowed for existing business relationships within 24 months Penalties up to CAD $10M per violation For full compliance details, edge cases, opt in copy templates, and STOP/HELP response templates : see [references/compliance.md](references/compliance.md). Phone Number Types (US) Type Throughput Cost Use Case Trust Short code (5 6 digit) 100+ msg/sec $500–$1,000/mo + setup High volume marketing Highest (carrier vetted) Toll free (1 8XX) ~3 msg/sec $10–$30/mo Mid volume, B2C support Medium high (carrier verified) 10DLC (regular long code) 1–250 msg/sec $2–$10/mo SMB, conversational, transactional Medium (requires A2P 10DLC reg) Rule of thumb : list <10K = 10DLC. List 10K–100K = toll free. List 100K+ = short code. Core Principles 1. Every send has a real cost SMS isn't free. At $0.0075–$0.04 per send + carrier fees, a 100K send costs $750–$4,000. This forces relevance — you can't "blast." Segment hard. 2. Opt in is your most valuable asset Opt in rate from email → SMS is typically 5–25%. A high quality SMS list of 10K beats a low quality list of 100K. Optimize opt in quality, not volume. 3. Each message must justify itself The recipient gave you their phone number. Every send should pass: "would I be glad I got this text?" If no, don't send. 4. Brevity + clarity 160 GSM 7 characters = 1 SMS segment. 161+ chars = 2 segments (you're billed for 2). Emojis force UCS 2 encoding (70 chars per segment). Plan for segment count. 5. One CTA, one link Short links are mandatory ( klvy.co , txt.attn.tv , branded short domain). Track UTM params on every link. 6. Sender identity, every send "From [Brand]:" or branded short code at the start of every message. Even on automated flows. Recipients can't see "from" address — they need it inline. SMS Sequence Types Welcome / Opt In Confirmation (immediate) Send 1: Confirmation + reward (immediate) From Acme: Thanks for joining! Here's 10% off: ACME10. Use at checkout: acme.co/sale. Reply STOP to opt out. Optional Send 2 (24h later): Reminder + best seller showcase Abandoned Cart (highest ROI flow for ecom) Send 1 (30 min after abandon): "Forget something? Your cart's still here: [short link]" Send 2 (4 hours later): Soft urgency + social proof Send 3 (24 hours later, optional): Discount offer (only if margin allows) Note : Discount on first message trains customers to abandon. Reserve discount for Send 2 or 3. Browse Abandonment Send 1 (1 hour after browse): Product + "Thinking it over?" + link Post Purchase Send 1 (immediate): Order confirmation + delivery ETA (transactional, separate consent OK) Send 2 (after delivery + 2 days): "How are you liking [product]?" + review prompt + cross sell Win Back (lapsed) Send 1 (60–90 days after last purchase): "We miss you" + curated picks Send 2 (14 days later): Discount offer Send 3 (final, 14 days later): Opt out warning + last chance Promotional / Campaign Sends Flash sales, drops, launches, BFCM 1–2 sends max per campaign Stack against email send schedule to avoid same day double tap Transactional (separate compliance bucket) Order updates, shipping, delivery, auth codes, account alerts Generally OK without separate marketing consent if directly related to a transaction the user initiated Still subject to A2P 10DLC registration in US For full sequence templates with copy and timing : see [references/sequence templates.md](references/sequence templates.md). SMS Copy Guidelines Structure 1. Sender ID ("From Acme:" or brand short code) — required 2. Hook — first 5 words decide if they read on 3. Value — what's in it for them, specifically 4. CTA + short link — single action, single URL 5. Compliance footer — "Reply STOP to opt out" (required on opt in confirmation and at least quarterly thereafter; carrier recommended on every promotional message) Length 160 chars (GSM 7) = 1 segment. Aim here. 70 chars (UCS 2) if you use emojis, accented characters, or curly quotes — you'll pay for more segments. 161–306 chars = 2 segments (concatenated SMS). Acceptable for richer messages, but you're paying double per send. MMS (image + up to 1,600 chars) = 3–5× the SMS cost. Use sparingly for high impact moments. Voice Conversational, not corporate. SMS feels personal — write like you're texting a friend. No subject line, no formatting, no marketing speak. Emojis are fine in moderation (one per message, situationally). ALL CAPS reads as shouting. Avoid except for explicit codes (e.g., "Use ACME10"). Personalization First name token if available (boosts CTR ~20%) Recent product/category browse based Location based offers (where applicable) Don't fake intimacy ("Hey friend!") — it backfires For complete copy patterns by sequence type with character counts : see [references/sequence templates.md](references/sequence templates.md). Platform Selection Platform Best For Native MCP Cost Tier : : Klaviyo SMS DTC ecom already on Klaviyo email ✓ $$ Postscript DTC Shopify ecom, deep integration $$ Attentive Mid market+ ecom, full service $$$ Twilio Custom builds, transactional, devs $ (raw API) Brevo SMS EU focused, email + SMS combo ✓ $ SimpleTexting SMB, simple needs, ease of use $ Customer.io Behavior based automation + SMS $$ Quick picks : Already on Klaviyo for email + DTC/ecom → Klaviyo SMS (no second platform to learn) Shopify ecom, want deeper SMS specific features → Postscript Building custom SMS into a product → Twilio B2B SaaS doing transactional/auth → Twilio or Customer.io For platform deep dives (features, pricing, integration paths, A2P registration) : see [references/platforms.md](references/platforms.md). Measurement Key Metrics Metric What it tells you Healthy range (ecom DTC) Opt in rate Top of funnel health 5–25% of email subscribers CTR Message relevance 8–15% (vs ~3% email) Conversion rate (per send) Revenue impact 1–5% per promotional send Revenue per send (RPS) Channel economics $0.20–$2.00 Opt out rate per send Audience fatigue <2% per send, <0.5% for promotional Cost per send Channel cost discipline $0.0075–$0.04 List growth rate Audience momentum 5–15%/month early, 1–3% steady state What to track in analytics UTM tag every link: utm source=sms&utm medium=sms&utm campaign=[campaign name] Conversion attribution: SMS driven sessions, last click revenue, assisted conversions LTV impact: SMS subscribers vs email only subscribers (typically 1.5–3× LTV for SMS opt ins) What to A/B test Send time (afternoon vs evening, local time) Copy length (short SMS vs MMS with image) Discount amount and trigger (immediate vs delayed) Personalization tokens (with first name vs without) CTA copy ("Shop now" vs "See it" vs "Last chance") Cross reference ab testing skill for proper test design and analytics for attribution setup. Output Format When the user asks for an SMS plan, return: 1. Compliance check : Are they registered for A2P 10DLC (if US)? Is the opt in mechanism compliant? Flag blockers first. 2. Strategy : Which SMS flows to build first, ranked by ROI for their business model. 3. Sequence designs