The POST /environments/{environmentId}/templates/{templateName}/contents operation can be used to create a new customized text message content resource associated with the template specified in the request URL.

The size restriction on the content value is derived from the content encoding. UC-2 encoding is used for messages that contain non GSM-7 characters, and in this case, a size restriction of 67 characters is enforced. However, GSM-7 encoded messages may contain up to 153 characters.

The sender value may contain only alphanumeric characters and spaces, and its length may be up to 11 characters.

In some countries, including the US, it is impossible to send an SMS with an alphanumeric sender ID. For those countries, the sender ID must be empty. For international alphanumeric sender support, please refer to https://support.twilio.com/hc/en-us/articles/223133767-International-support-for-Alphanumeric-Sender-ID.

Due to India’s pre-registration laws, “PingID” is always used as the sender ID for SMS recipients in India.

In addition, the variables restrictions should apply to text message notification content.