Conversational SMS: Who Answers When a Shopper Texts Back

Conversational SMS is two-way texting: a brand’s text invites a reply, and the reply gets an answer from an AI agent, a vendor-staffed agent or the brand’s own team. It needs a sending number that can receive texts, and the branded sender IDs that Klaviyo’s help center names as the default in sixteen countries cannot.

Klaviyo’s help article on sending numbers says it plainly. Branded sender IDs, which show a brand’s name where a phone number would be, are “the default option in Klaviyo” for the UK, Ireland, Germany, France, Austria, Spain, Switzerland, Denmark, Norway, Finland, Sweden, Italy, Portugal, Poland, Australia and Mexico. The same article’s availability table, which stars branded sender IDs as a default number type, also ticks them for the Netherlands and Luxembourg, two countries that list leaves out. Of that ID, the article says “it cannot receive messages, so your recipients cannot text you back”, and its list of features this rules out includes “SMS conversations/two-way messaging”. Long codes, which look like ordinary phone numbers, “are able to receive inbound messages”, but each one reaches a single country, and the same article says non-default numbers “require a paid plan”. Postscript draws its line by geography instead: “Two-way conversations are available for subscribers based in the United States and Canada”, and a brand texting the United Kingdom or Australia is told to ask for a dedicated number for that region. This is a fact about the channel, not about the audience: it decides whether a reply can arrive at all, before any question of which shoppers a message reaches or who answers. This guide reads Postscript’s, Klaviyo’s, Attentive’s and Emotive’s own pages and help centers as served on October 19, 2026. It is published by Relvino, which decides per shopper across email, SMS and pop-ups and competes with some of these vendors for the same budget, so read it as informed but interested.

What makes SMS conversational

Klaviyo’s SMS glossary defines the idea in one line: “conversational messaging is a back-and-forth conversation that takes place via text.” Its description of Klaviyo’s own two-way feature puts the shopper first: “You cannot initiate a conversation; only reply after a customer texts you first.” A campaign or flow text is therefore an invitation, and the conversation begins when the shopper answers it. Klaviyo’s guide to its AI agent on SMS turns the same point into advice: “Customer Agent only works if customers reply.”

So a conversational text is written to be answered, and every answer needs a reader that can reply or pass it to a person who can. The vendors differ most on that second half.

In North America the number is rarely the obstacle: Klaviyo says toll-free numbers “are the default sending numbers in Klaviyo for the US and Canada”, and its feature table marks them as able to receive SMS. The gap opens for brands that sell into Europe or Australia from a North American setup. A shopper in Germany who gets a cart text from Klaviyo’s default branded sender ID has no number to reply to.

Who answers the reply at four Shopify SMS vendors

The four vendors below sell conversational SMS to Shopify brands, and each puts a different kind of responder on the other end of the thread. Each description comes from the vendor’s own product page or help center.

Postscript: an AI agent, or the brand’s own inbox

Postscript’s answer is Shopper, which its product page describes as “a suite of specialized AI agents”. One of them, Responses, “handles conversations: answering questions, working through objections, sending product recommendations, and closing the sale in real time when a subscriber texts in.” The same page says brands onboarding to Shopper start with Brand Center and Shopper Responses. Replies also land in a Conversations tab, where Postscript’s help center says it centralizes inbound messages “along with responses to your campaigns and automations”, and a brand can forward them to a support email address or to help desks including Gorgias, Zendesk, Gladly and Kustomer. A human reply from that tab is metered like any other send: “Sending responses counts as usage, just as sending a campaign or automation would.”

Klaviyo: an AI agent inside its service product

Klaviyo’s Customer Agent on SMS is, in its help center’s words, “A 24/7 AI assistant that responds to inbound SMS messages to answer questions, recommend products, and resolve common issues”. Klaviyo’s launch post says the agent “lives within Klaviyo Service”, and the SMS guide lists an “Active SMS plan” as a requirement and adds that “SHAFT brands cannot activate Customer Agent on SMS”. A brand without the agent still gets its replies: “any message sent to your number that doesn’t include a keyword appears as a Helpdesk ticket.”

Attentive: human agents first, then AI beside them

Attentive’s Concierge began as a staffed service. Its Concierge FAQ, last updated in April 2024, says “a real, living human being at Attentive reads and responds to subscriber messages on your behalf”, lists agents online “7 days a week from 8am ET - 12am ET (16 hours per day)”, and says “Concierge agents don't have access to data about your customers or their orders”. A help article updated in September 2025 describes “Concierge powered by AI”, which “can read and respond to subscriber messages on your behalf”. The Concierge product page today describes “live agents and conversational AI working together”, responses 24/7, and says subscriber purchase history and browsing behavior help pick the moment to recommend. The pages were written at different times and do not agree on hours or on what the responder can see; a brand evaluating Concierge should ask which version it would be buying.

Emotive: people with software, now part of Privy

Emotive’s conversational texting page says “Emotive Automation is not a bot, it’s real humans with AI superpowers” and that “Proprietary technology enables our sales agents to answer questions, offer deals, and drive conversions at lightning speeds.” Emotive’s knowledge base adds the brand’s side: its conversational best-practices page tells brands to help customers with questions in Emotive’s Conversations tab or a help desk integration. Privy announced on July 8, 2025 that it “has acquired Emotive”, and its announcement promises 1:1 customer conversations alongside email and SMS campaigns in a single dashboard.

That is three models. Postscript and Klaviyo sell an AI agent the brand configures, which hands hard cases to the brand’s own team. Attentive runs the responder itself, human in its older pages and human plus AI in newer ones. Emotive sells people working with software.

Conversational SMS vendors compared

Quoted phrases are from each vendor’s own pages; every other cell is this guide’s summary of those pages.

• Postscript · Who answers a reply: Shopper Responses, an AI agent; without it, the brand in the Conversations tab · Where an unanswered reply goes: A ticket in Gorgias or Zendesk, after the shopper confirms · What the brand’s team receives: “the last 10 messages from the SMS conversation” · Are inbound texts billed?: Yes, at the standard or negotiated message rate since January 1, 2026
• Klaviyo · Who answers a reply: Customer Agent, an AI agent; without it, a Helpdesk ticket · Where an unanswered reply goes: The helpdesk set in handoff settings, or a closeout message · What the brand’s team receives: A transcript of the Customer Agent conversation · Are inbound texts billed?: “inbound messages do not cost you”
• Attentive · Who answers a reply: Concierge: human agents (2024 FAQ), with an AI version described in a 2025 article · Where an unanswered reply goes: An escalation email to an address the brand sets · What the brand’s team receives: The escalated case by email, answered through the agent or the Conversations Inbox · Are inbound texts billed?: Not stated on the pages read

Where a reply goes when the responder cannot answer it

Every conversational program meets replies it should not answer itself: a refund, a damaged order, a legal threat. The vendors document the route out in detail, and the details differ in ways a support team will feel.

Postscript’s escalation article walks through the steps. Shopper first asks the subscriber whether to connect them to the support team, then “creates a ticket in Gorgias or Zendesk. The ticket includes the last 10 messages from the SMS conversation so your agent has full context.” While the ticket is open, “Shopper pauses and stops sending automated replies”, and the support agent’s answer “is delivered to the subscriber as an SMS in the same thread.” Then the thread passes back: “Once the agent closes the ticket, Shopper automatically resumes. If the ticket isn't closed, Shopper resumes after 24 hours.” A ticket nobody closes over a weekend puts the AI back in the thread after 24 hours, whether or not a person has answered. The article also notes that “SMS rates apply to messages sent through the Gorgias or Zendesk integration”, so support agents are asked to keep replies short.

Klaviyo puts the decision before the reply. Its escalation rules article says “Escalation rules are evaluated before Customer Agent generates a response. That means a matching message never gets a Customer Agent reply”, allows up to 20 rules, and adds a limit: “Today, escalation rules use the same handoff destination for every triggered escalation.” On SMS, its settings article says “A ticket is created in your helpdesk and Customer Agent tells the shopper that a human will follow up.” A brand with no helpdesk can choose “Don’t hand off” and show a custom message instead.

Attentive’s route runs through email. The Concierge FAQ says an agent who cannot answer “escalates the message to your team”, and the brand can reply to the escalation email or answer from the Conversations Inbox. The email path has a twist: “Note that your reply doesn’t go directly to the subscriber; the Attentive Concierge agent uses your response to reply to the subscriber.” The brand’s answer reaches the shopper in the agent’s words. Attentive’s settings article adds that an escalated conversation is marked with a red bell and “temporarily locked”.

Who pays for the reply side

The shopper’s reply is billed at one vendor and free at another. Postscript’s billing article says that from January 1, 2026, “inbound messages will also incur a Postscript message charge at your standard or negotiated rate”, and that this “applies to inbound replies from automations, campaigns, and customer service conversations, as well as opt-ins.” Klaviyo’s billing article says the opposite for its texting plan: “Note that while skipped and inbound messages do not cost you, failed deliveries do.” Its AI agent sits on a separate meter, covered in the Klaviyo AI marketing agent guide, and its SMS guide adds that the agent’s own replies use SMS segments at standard SMS billing. A brand that answers texts by hand does not have to buy Helpdesk: Klaviyo says an account that ends its Helpdesk trial without buying moves to Inbox, a free help desk that still handles text messages. Klaviyo’s texting plan is covered in the Klaviyo SMS marketing guide, and the per-segment price of an outbound text in the SMS vs email marketing guide.

What to check before switching it on

The pages above suggest six questions that separate conversational SMS products faster than a demo does.

• Can every sending number receive? Check each country the brand texts. A branded sender ID cannot, and a long code covers one country.
• Who answers, and when? An AI agent the brand configures, a team the vendor staffs, or the brand’s own people, and during which hours.
• What can the responder see? Order history, browsing, the last messages in the thread, or only the brand’s help pages.
• Where does an unanswerable reply go? A help desk ticket, an email, or a closeout message, and with how much of the thread attached.
• When does the automation take the thread back? On ticket close, after a fixed time, or never.
• Who pays for each direction? Inbound texts, human replies sent as SMS, and AI conversations can each be a separate line.

Consent sits underneath all six; the rules for texting shoppers at all are covered from the statutes and carrier codes in the SMS marketing best practices guide. For the SMS vendors themselves, see Attentive competitors and Postscript alternatives.

A conversation is three systems, not one

Product pages sell conversational SMS as one feature; the help centers describe three pieces that must work in order. A number that can hear the reply, settled by carrier and country before any software is chosen. A responder, whether a model, a staffed team or the brand’s own desk, each with its own hours and its own view of the customer. And a route back, which decides what the brand’s team receives and when the automation picks the thread up again. A brand that checks only the middle piece can buy an excellent responder that, in some markets, nobody can text.

Frequently asked questions

What does it mean to use SMS for communication?

SMS stands for short message service, the plain text channel every mobile phone supports. Klaviyo’s SMS glossary describes an SMS as a text with only text or symbols such as emojis, while a text carrying an image or GIF is MMS. Marketing texts are application-to-person traffic, which the same glossary says includes marketing communications and describes as messages a person receives from an application and is typically not expected to answer. Using SMS for communication, rather than only for announcements, means accepting replies, and that needs a sending number able to receive them and someone or something to read them.

What is an example of conversational SMS?

Klaviyo’s help center gives one: an abandoned cart text that read “You left the compression leggings behind! Any question, reply here”, and a shopper who answered “are they machine-washable?”. Klaviyo says its Customer Agent can read the messages exchanged between the brand and the shopper over the previous 48 hours, so it can tell the question is about the leggings. The example works because the first text asks for a reply about one product, and the responder can see which product that was.

Does conversational SMS work outside the United States and Canada?

It can, with a number that receives texts, and that depends on the country. In Klaviyo a long code can receive replies but reaches only one country, and in Australia and Ireland it must be verified first, which Klaviyo says takes one to three business days. If a brand has both a long code and a branded sender ID, Klaviyo says the long code typically takes precedence. For France, both of Klaviyo’s country tables list no SMS number type other than the branded sender ID. Klaviyo also offers RCS: once a brand’s RCS agent, a verified branded sender, is active in a country, Klaviyo says campaigns, flows and conversations go out over RCS to capable phones, and it says carrier review of a new agent typically takes four or more weeks.

What happens if a shopper texts STOP during a conversation?

At Klaviyo and Attentive, keywords are handled before the responder sees the text. Klaviyo’s Customer Agent does not answer messages that match compliance keywords such as STOP and HELP, that trigger subscribe or unsubscribe logic, or that trigger an SMS keyword automation. Attentive’s Concierge FAQ says agents read subscriber messages that do not include a support or other keyword. Keywords also depend on the sending number: Klaviyo lists keywords, including opt-out keywords like STOP, among the features that need a number able to receive SMS, and says recipients of a branded sender ID can opt out through an unsubscribe link.

Can a shopper who is not an SMS subscriber get a text reply?

Not at Klaviyo or from Attentive’s Concierge, according to their help centers. Klaviyo’s Helpdesk guide says that for text message tickets the customer must be an SMS or RCS marketing subscriber before the brand can reply, and suggests an auto-responder telling non-subscribers to opt in; web chat and email replies need no marketing consent. Attentive’s Concierge FAQ says a reply from someone who has only opted in to transactional messages is not sent to a Concierge agent. The consent rules behind this are covered in the SMS marketing best practices guide.

How long does migrating to Relvino take?

The technical cutover takes about 30 minutes: connect the Shopify store, point the sending domain and SMS number, and shopper data ingests automatically, with no flows to rebuild. Revenue is then measured in a 14-day pilot. A brand should not release its old sending number in a hurry: Klaviyo’s sending-numbers article says released toll-free numbers cannot be recovered, and that releasing the toll-free number shown for the US also removes it for Canada.