Get conversation

Initiate a new direct message conversation with a specified user. If a conversation already exists with the recipient, the message is added to the existing thread. Supported platforms: X/Twitter, Bluesky, Reddit, and WhatsApp. Other platforms return PLATFORM_NOT_SUPPORTED. WhatsApp: this is the endpoint for sending an approved template message to a phone number. Provide templateName, templateLanguage, and templateParams (variable values for the text header, body and dynamic URL buttons, in that order), with the recipient phone in participantId. A template is required because WhatsApp does not permit freeform messages to open a conversation; a missing template returns TEMPLATE_REQUIRED. Templates with media headers (image, video, document) are handled automatically: Zernio reads the approved template definition and fills the header at send time with the template's approved sample asset. To send a DIFFERENT asset per message (e.g. a distinct invoice PDF for each recipient), pass the headerMedia field with a public link (or a Meta media id); it overrides the sample for that send. Calling this for a number you already have a thread with simply sends the template into that thread, which also makes it the way to re-engage a contact after the 24-hour customer-service window has closed. Once the recipient replies (opening the 24h window), send freeform messages with the send-message endpoint (POST /v1/inbox/conversations/{conversationId}/messages). Template fields are accepted on the JSON body only, not on multipart requests. DM eligibility (X/Twitter): Before sending, the endpoint checks if the recipient accepts DMs from your account (via the receives_your_dm field). If not, a 422 error with code DM_NOT_ALLOWED is returned. You can skip this check with skipDmCheck: true if you have already verified eligibility. X API tier requirement: DM write endpoints require X API Pro tier ($5,000/month) or Enterprise access. This applies to BYOK (Bring Your Own Key) users who provide their own X API credentials. Rate limits (X/Twitter only): X's DM API enforces 200 requests per 15 minutes, 1,000 per 24 hours per connected X account, and 15,000 per 24 hours per X developer app (shared across all DM endpoints). These limits do NOT apply to other platforms. WhatsApp sends are governed by Meta's per-number messaging tiers (unique business-initiated conversations per 24 hours) and per-number throughput instead.