Signal is a mobile and cross channel marketing platform. Create two-way SMS campaigns and interface directly with email marketing from within the same system. Use email to call customers to opt into a text message program. Or, trigger emails based on mobile interaction.
Signal supports multiple types of APIs for different purposed. Use REST or SOAP to send messages. Receive messages and subscription alerts via webhooks.
The platform is geared toward businesses and agencies, with subscriptions starting at $500 per month.