
A custom sender ID, also known as an alphanumeric sender ID, enables users to set a business name as the sender ID for one way organisation-to-consumer messages. This is only supported in certain countries and are up to 11 characters long, and support uppercase and lowercase ASCII letters and digits 0-9.[12] Senders aren’t allowed to use digits only as this would mimic a shortcode or virtual number that they don’t have access to. Reputable bulk SMS providers will check customer sender IDs beforehand to make sure senders are not misusing or abusing them.

A single SMS message has a maximum size of 1120 bits. This is important because there are two types of character encodings, GSM and Unicode. Latin-based languages like English are GSM based encoding, which are 7 bits per character. This is where text messages typically get their 160 character per SMS limit.[13] Long messages that exceed this limit are concatenated. They are split into smaller messages, which are recombined by the receiving phone.

In order to gain their mobile number, they will have to have a great deal of trust in you and a pre-existing relationship will help. They also need to know that what you'll be sending them via SMS message is exclusive offers, not the same offer that you give via email and social media. Be clear with your customers and use the following guidelines when introducing SMS marketing to your customers: