curl --request POST \
  --url https://api.cleartalk.ai/agency/twilio/a2p-campaign-registration \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "brandRegistrationSid": "<string>",
  "messagingServiceSid": "<string>",
  "campaignId": "<string>",
  "optInMessage": "<string>",
  "optOutMessage": "<string>",
  "helpMessage": "<string>",
  "optInKeywords": [
    "<string>"
  ],
  "optOutKeywords": [
    "<string>"
  ],
  "helpKeywords": [
    "<string>"
  ]
}
'

{
  "sid": "<string>",
  "account_sid": "<string>",
  "messaging_service_sid": "<string>",
  "brand_registration_sid": "<string>",
  "campaign_id": "<string>",
  "campaign_status": "<string>",
  "opt_in_message": "<string>",
  "opt_out_message": "<string>",
  "help_message": "<string>",
  "opt_in_keywords": [
    "<string>"
  ],
  "opt_out_keywords": [
    "<string>"
  ],
  "help_keywords": [
    "<string>"
  ],
  "date_created": "<string>",
  "date_updated": "<string>",
  "url": "<string>"
}