--- title: "SMS vs email: what's different" description: "Consent, quiet hours, per-segment billing, reach, and no opens or clicks. Read this once before your first SMS." url: https://www.unitpost.com/guides/sms-vs-email section: Guides updated: 2026-10-06 --- # SMS vs email: what's different ## SMS vs email: what's different > Consent, quiet hours, per-segment billing, reach, and no opens or clicks. Read this once before your first SMS. SMS runs on the same Unitpost you already use for email: same contacts, same segments, same API key and error envelope, same webhooks. But the channel itself is governed by carriers and regulators rather than inbox providers, and that changes seven things. Each is covered in depth in its own guide; this page is the map. ### Consent is opt-in, not opt-out Email marketing is opt-out by default: you may send until someone unsubscribes. SMS is the reverse. A marketing SMS needs the recipient's prior express consent on record before the first message, and a send without it is skipped with the reason no_marketing_consent rather than attempted. Transactional SMS (receipts, alerts, verification codes) does not need marketing consent. Record consent where the recipient actually gave it: your signup form (POST /v1/contacts/{id}/sms-consent with a source), a keyword they texted, or the hosted preference page. Never mark a list as opted in on their behalf. - STOP opts the number out of the SMS channel entirely. It never touches the contact's email subscription, and vice versa. - HELP returns your program's help text (your brand name, how to reach support, how to stop). - START re-opts the number in. Carrier keywords are handled for you; do not build keyword handling yourself. ### Quiet hours Email lands whenever you send it. Marketing SMS respects the recipient's local quiet hours: a message queued at midnight is deferred to the morning window, never dropped and never sent at 2am. The recipient's window comes from their phone number's country and region. A deferred message shows the reason quiet_hours_deferred; there is nothing to fix. Transactional messages are not window-gated. ### Billing is per segment, from the wallet Email counts against your plan's monthly volume. SMS is billed per segment from your workspace's messaging wallet: 160 GSM-7 characters fit one segment (153 each when a message spans several); Unicode messages fit 70 (67 each when split). The composer and the template editor show the segment count as you type. A skipped recipient is never billed, and a campaign pauses rather than overdrawing the wallet. Number rental is a recurring card line item, not a wallet debit. ### Reach: numbers and Sender IDs A verified email domain can send to any inbox in the world. An SMS sending identity delivers to specific countries, by carrier rule. A US toll-free or 10-digit local (10DLC) number reaches US recipients only; a Canadian local number (instant, no registration) reaches Canada only. To reach other countries you enable an alphanumeric Sender ID: your brand name on the handset instead of a number, free, enabled per destination country. It is instant in most of Europe, Latin America, Asia-Pacific, and Africa; some countries (the United Kingdom, Spain, Singapore, and others) require a regulator registration that takes days to weeks; the United States, Canada, and China do not support Sender IDs at all. A recipient outside every sender's reach is skipped as out_of_reach, with the country and a link to the fix. See SMS Senders (/guides/sms-senders) for the full reach table. ### No opens or clicks Carriers report three things: sent (accepted by the carrier), delivered (confirmed on the handset), and failed, with a carrier reason when there is one. There is no open tracking, no click tracking, and no engagement rate to request; the SMS dashboard and the per-message page show delivery, not engagement. If you need a click signal, link to a page you control and measure there. ### Brand registration comes first Email setup is DNS records on a domain you own. SMS setup starts with a brand: your legal entity, website, and a contact email on that website's domain, which carriers or regulators approve before they will hand you a production number or a registered Sender ID. The brand page lists exactly which fields are still missing, and GET /v1/sms/brands returns the same status and missing list for scripts and agents. Creating a brand and requesting numbers are paid submissions made in the dashboard. See SMS Brands (/guides/sms-brands). ### Skip reasons: one vocabulary Email tells you about bounces and complaints after the fact. SMS tells you before you send who will be skipped and why, and every surface uses the same seven words: campaign preflight, the campaign page, the message log, error.code on GET /v1/sms/{id}, and reason on the sms.suppressed webhook. - out_of_reach: no sender on the message or campaign covers the recipient's country. Fix: request a sender for that country. - unsupported_country: inside reach, but Unitpost has no compliance rule for the country yet. Transactional still sends. - no_phone: the contact has no SMS number. Fix: add one to the contact. - opted_out: STOP, the suppression list, or an unreachable number. The recipient re-opts in by texting START or from the preference page. - no_marketing_consent: marketing without express consent on record. Fix: record consent the recipient actually gave. - quiet_hours_deferred: held for the recipient's local window. Delayed, not dropped; nothing to fix. - sender_not_active: the sender lost approval or was released. Fix or replace the sender, then resume. > **Where to go next:** Set up the identity in SMS Brands (/guides/sms-brands) and SMS Senders (/guides/sms-senders), write a template in SMS Templates (/guides/sms-templates), then send one message from SMS Messages (/guides/sms-messages) or a segment from SMS Campaigns (/guides/sms-campaigns). ## Related - [SMS Messages](https://www.unitpost.com/guides/sms-messages): Send transactional and marketing SMS, and follow each message's delivery live. - [SMS Brands](https://www.unitpost.com/guides/sms-brands): The business identity carriers register before they will approve a phone number. - [SMS Senders](https://www.unitpost.com/guides/sms-senders): The phone numbers and Sender IDs your SMS messages originate from.