15 Workflows Built
A U.S.-based holistic wellness practice needed to send 15 scheduled SMS messages to contacts via OpenPhone, but faced a hard platform limit of 10 messages per minute with no override available. INSIDEA resolved this by building 15 sequential HubSpot workflows with percentage-based branching, time-delayed sends, and reply-based exit logic to stay within platform constraints. The result was a fully automated, scalable SMS campaign system that delivers all 15 messages in order, stops sending when a contact replies, and requires no manual intervention to operate.
Numbers That Tell the Story
- Industry
- Healthcare
- Location
- United States
- Service
- HubSpot Workflow Automation
- Timeline
- 4-6 Weeks
A U.S.-based holistic wellness practice offering telehealth and in-person therapy and coaching needed a way to send a scheduled bulk SMS campaign of 15 messages to contacts via OpenPhone, integrated within their existing HubSpot CRM environment.
A Platform Limit With No Native Workaround
The wellness practice needed to send 15 SMS messages to a contact list at a specific, scheduled time. While OpenPhone was already integrated with HubSpot, the platform enforces a hard limit of 10 SMS messages per minute, a restriction confirmed by OpenPhone support with no override available. Standard bulk sending approaches were not viable. The solution required a custom-engineered workflow architecture that could respect this rate limit while still delivering all 15 messages reliably and in sequence, without requiring manual effort.
Bulk SMS Scheduling Requirement
The practice needed all 15 messages sent to contacts at a specific scheduled time, with no native bulk SMS scheduling feature available within the OpenPhone-HubSpot integration.
Hard Platform Rate Limit
OpenPhone enforces a strict limit of 10 SMS messages per minute. With no override option available, any solution needed to be engineered entirely within these constraints.
API-Based Trigger Dependency
The SMS sending process required updating a custom numeric field in HubSpot to initiate the workflow. This added complexity to the trigger logic and required precise property management across all 15 message steps.
No Scalable Architecture in Place
There was no existing automated system capable of handling sequenced, rate-compliant bulk messaging. Every send would have required manual effort, making the campaign unsustainable at any meaningful contact volume.
A 15-Workflow HubSpot Architecture Built for Scale
INSIDEA designed and implemented a fully automated SMS campaign system using HubSpot workflows, engineered specifically to work within OpenPhone’s rate limitations. Rather than attempting a single bulk send, the team built 15 separate sequential workflows, one per SMS message, connected end-to-end. A percentage-based branching mechanism distributed contacts across multiple paths to ensure no more than 10 messages were sent per minute. Time delays were applied within each branch, and a reply-based exit condition was built in to stop the sequence automatically when a contact responded.
SMS Campaign Architecture
Fifteen individual HubSpot workflows were created and chained sequentially. Each workflow corresponds to one SMS message, with contacts automatically moving to the next workflow upon completion of the previous one.
Percentage-Based Rate Limiting
To comply with OpenPhone's 10-message-per-minute cap, enrolled contacts are split across 20 branches using HubSpot's percentage-based split action. This ensures the delivery rate never exceeds platform limits, regardless of contact volume.
API Trigger and Property Management
A custom numeric property (number of times SMS sent) acts as the campaign controller. Updating this property to 1 triggers the first message; subsequent workflows increment the value to deliver each successive SMS in the correct order.
Reply-Based Exit Logic
If a contact replies to any message in the sequence, they are automatically unenrolled from all remaining workflows. This prevents unwanted follow-up sends, improves the contact experience, and supports downstream sales engagement tracking.
What the Solution Delivered
The engineered workflow system resolved a previously unsolvable operational challenge. The practice now runs fully automated, rate-compliant SMS campaigns without manual involvement, with complete visibility into delivery and response at every step.
Fully Automated SMS Workflows Deployed
- Compliance with messaging limits
- Delivery within platform constraints, no failed sends
- Improved contact experience
- No follow-up spam after reply
- Campaign control
- Start/stop via single property update
- Engagement tracking
- Full visibility on send and reply status per contact
Built for Teams Facing the Same Constraints
This approach is particularly valuable for service businesses and healthcare-adjacent organizations that rely on HubSpot as their CRM and need to run scheduled, multi-message SMS campaigns at scale without exceeding platform-imposed API limits.
- Healthcare and wellness practices that use HubSpot and OpenPhone to manage patient or client outreach via SMS
- Service businesses running appointment reminder sequences or onboarding drip campaigns through OpenPhone
- Marketing and operations teams that need to trigger bulk SMS sends at a specific time without manual intervention
- Companies using HubSpot workflows who have hit API rate limits from third-party integrations and need a compliant architecture
- Any organization that needs reply-based exit conditions to ensure contacts are not sent follow-up messages after responding
Answers to the questions teams ask before they start
How can HubSpot workflows be used to send bulk SMS through OpenPhone?
HubSpot workflows can be configured to trigger SMS sends via OpenPhone by updating a custom numeric property that initiates each send. To manage OpenPhone’s 10-messages-per-minute rate limit, contacts are distributed across multiple workflow branches using HubSpot’s percentage-based split action. Each branch adds a time delay before sending, ensuring delivery stays within platform constraints while all contacts receive the messages.
What is OpenPhone's SMS rate limit and how do you work around it?
OpenPhone allows a maximum of 10 SMS messages per minute. This is a hard platform restriction with no override option. The recommended workaround is to use HubSpot’s branching and delay logic to distribute contacts across multiple paths, so that each branch sends no more than 10 messages in a given minute. This approach requires no changes to the OpenPhone configuration and operates entirely within HubSpot’s workflow tools.
How do you stop a HubSpot SMS sequence when a contact replies?
Reply-based exit logic can be implemented within HubSpot workflows by configuring an unenrollment condition triggered when a contact responds to an SMS. Once the condition is met, the contact is automatically removed from all subsequent workflows in the sequence, preventing further messages from being sent. This protects the contact experience and reduces the risk of over-messaging.
Is it possible to send a 15-step SMS campaign automatically through HubSpot?
Yes. A 15-step SMS campaign can be fully automated in HubSpot by creating 15 separate sequential workflows, each responsible for one message. The workflows are connected so that completing one automatically enrolls the contact in the next. A custom numeric property tracks progress through the sequence, ensuring each contact receives the correct message at the correct step without any manual input.
What are the benefits of using modular HubSpot workflows for SMS campaigns?
Modular workflow design, where each SMS message has its own dedicated workflow, makes campaigns easier to manage and maintain. Individual messages can be edited, paused, or replaced without disrupting the rest of the sequence. It also provides granular visibility into performance at each step, making it easier to identify where contacts drop off or respond and to optimize future campaigns accordingly.
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