An SMS marketing API lets another system tell your messaging platform to send a text, or lets your messaging platform tell another system that a text has arrived. You need one when the event that should trigger a message lives outside your CRM: a booking in a practice management tool, a signed document, a payment in an accounting package. This article explains when a company actually needs API-driven texting, how to connect it to the levelpartner.ai platform through webhooks and workflows, and when the honest answer is that you do not need code at all.
The question to ask first
Most requests for an SMS API come from a developer or an operations lead who has spotted a gap: something happens in system A, and a customer should be texted about it. Before anyone writes code, check whether system A can be replaced by a feature the platform already has. Calendars, forms, payments, pipelines and invoices all trigger workflows natively, with no integration.
If the event genuinely has to stay in another system, you have two options. The other system can call the platform when the event happens, which is the inbound webhook route. Or a developer can call the platform's API directly, using credentials your administrator issues, to create or update a contact and send a message. The first is simpler, easier to maintain and visible to non-developers. The second gives more control and suits teams with engineering capacity.
How webhook-triggered texting works
A workflow on the platform can start from the Inbound Webhook trigger, which gives the workflow a unique address. Your other system sends a small packet of data to that address when the event happens: the contact's name, mobile number and whatever detail the message needs. The workflow maps those fields, checks consent and sends the text.
The advantage is that the message wording, the timing, the opt-out rules and the follow up steps all stay inside a workflow your marketing team can read and edit. The developer only maintains the connection, not the copy.
Before you start
- A clear list of the events that should trigger a text, and which system owns each one.
- Confirmation that the source system can send webhooks, or a developer who can add that.
- A consent field on the contact that the workflow can check before sending.
- An SMS-enabled number on the platform with business messaging registration in place.
- A test contact with a phone you control.
How to set up the webhook trigger
- Open or create a workflow and choose the Inbound Webhook trigger.
- Copy the unique webhook URL the platform creates.
- Set the source system to send a POST request with JSON to it.
- Send a test request from the source system.
- Select the received data and map it to workflow fields.
- Click Save Trigger.
Below the trigger, add a condition that stops the workflow if the contact has not agreed to texts, then the Send SMS action with the mapped fields in the message, and any follow-up steps such as a reminder or an internal task. Publish, then fire a real event end to end and check the text, the contact record and the conversation.
When to call the API directly instead
Direct API access suits cases where the other system needs a response, such as confirming that a message was queued, or where volume and logic are complex enough that a developer would rather manage them in code. Typical examples are a client portal that sends one-time codes or a custom quoting tool that texts a link to a generated quote.
The trade-off is maintenance. Code that sends marketing messages has to respect consent and opt-out status just as a workflow does, and that logic is now in two places. For most firms in our four industries, workflows handle the marketing side and the API is reserved for genuinely transactional messages. If you are deciding what counts as marketing, the article on promotional versus service texts sets out the line.
Suppose applications are tracked in a specialist case management tool that sends a webhook when a case reaches offer. The workflow would text the client a short congratulations, send a review request three days later and create a task for the broker to call about protection. A build like this might take a developer a couple of hours and the marketing lead an afternoon. At around 120 cases a month, that is 120 sets of messages nobody has to type. The figures are illustrative.
What it replaces
API-driven texting replaces the manual step where someone sees an update in one system and remembers to text the client from another. In a 40 to 100 person firm, that step is often done by an administrator, inconsistently, and only in office hours. Wiring it once removes a daily task and makes the customer experience consistent regardless of who is on shift.
Time it takes each week
After launch, very little. Someone should check the workflow's execution history weekly for failures, which usually come from missing mobile numbers or changed field names in the source system. Budget fifteen minutes a week, and a short review whenever the source system is updated.
The mistake most people make
Sending marketing content through a path built for transactional messages. A developer builds a quick integration to send appointment confirmations, then someone adds an offer to the end of it. That message is now marketing, it needs marketing consent, and it bypasses every safeguard in your workflows. Keep the two paths separate. For the rules that apply to every marketing send, see what good SMS practice looks like.
When not to use it
Do not build an integration for a once-a-quarter campaign. Export the list, import it into Contacts and send through a bulk action. Do not use the API to bypass sending limits or registration rules. And if your team has no one who can maintain a webhook when the source system changes, keep the process inside the platform. For texts that respond instantly to inbound enquiries, which need no integration, read automatic replies to inbound texts.
Troubleshooting
The workflow never starts. The source system is sending to an old address or failing silently. Check its webhook log and resend a test event.
Contacts are created without a mobile number. The field mapping points at the wrong key in the payload. Re-run the sample and remap.
Texts send to people who opted out. Your consent condition is missing or checks the wrong field. Add a check on the contact's do not disturb status for SMS.
Duplicate contacts appear. The source system sends numbers in a different format. Standardise to international format before sending, or match on email as well.
Frequently asked questions
Do I need a developer to connect an SMS marketing API?
For webhook triggers, often not, if the source system has a webhook setting. For direct API calls, yes.
Can I receive inbound texts in another system?
Yes. A workflow triggered by a customer reply can send a webhook outwards with the message and contact details.
Is API sending billed differently from normal texts?
No. Messages are billed as used as usage, whichever route triggers them.
Should transactional and marketing texts use the same number?
They can, but keep their workflows and consent checks separate so a service message never carries promotional content to someone who has not opted in.