Twilio - Brings voice and messaging to your web and mobile applications.
E-goi - Email Marketing companies, SMS Marketing, software email marketing.
TelAPI - Build Apps With Our Cloud Based SMS & Voice API
Maytapi - Serverless Whatsapp Api with Chat and Agent support.
SMSAPI - SMSAPI.com is browser platform for bulk SMS and other SMS marketing solutions.
Tellephant - Helping you build incredible chatbots and integrate WhatsApp, Google, Facebook, SMS and more to your communication stack in seconds. All at the cheapest rates out there.