4151234567@txt.att.net To determine the SMS gateway domain, e.g., txt.att.net, may require research - but most users know who their carrier is. Observe that the telephone number in this example for a US number is expressed as ten (10) digits, without the country code (1) and without dashes or other separator characters when composing the email address. The country code is not needed, as the 10-digit telephone number, together with the email domain, are sufficient to send the email from any location in the world. It is useful to perform a character count before sending the message to ensure that it is within the 160-character limit. If it exceeds the limit, the SMS gateway should break the message into a set of consecutive 160-character, or shorter, messages to the mobile equipment, although the breaks may occur in the middle of words. A message sent with an email client can be simultaneously addressed to multiple mobile telephones - just as text messages sent in the usual manner between mobile telephones can be sent to multiple recipients. SMS gateway domains for other carriers (US-based): SMS gateway domains for Canadian carriers: SMS gateway features There are several applications for SMS gateways, including: Bulk/mass SMS messaging communications commonly used for customer care to marketing campaigns Two-way SMS messaging, designed for the exchange of messages from clients to a customer portal To enable the development of an SMS widget for newsletters and updates API allowing systems to integrate with 3rd party systems including common CRM, e-commerce, ERP, and internal platforms For multi-factor authentication or two-factor authentication using SMS as a channel for delivering one-time-passwords (OTPs) See also Kannel (telecommunications) Videoconferencing Voice over IP References Mobile telecommunications Text messaging