from

string

Sender phone number in E.164 format (e.g., +1234567890). This is the phone number that will appear as the sender of the SMS. Supports template syntax with variables.

message

string

SMS message text to send. Supports template syntax with variables. Maximum length depends on carrier limits (typically 160 characters for single SMS, 1600 for concatenated).

to

string

Recipient phone number in E.164 format (e.g., +1234567890). Supports template syntax with variables.