Usage:

// .env file
> ISENDPRO_DSN=isendpro://apikey@default?from=FROM

where:
* APIKEY is your ISendPro API KEY
* FROM is your Sender Name

// config/packages/notifiers.yaml file
framework:
    notifier:
        texter_transports:
            isendpro: '%env(ISEDNPRO_DSN)%'

Then you can then use it like documented here https://symfony.com/doc/current/notifier/texters.html

ℹ️ For more information you can check ISendPro's docuementation:

• https://www.isendpro.com/api-envoi-sms-php
• https://www.isendpro.com/api-sms/doc-api-sms-restjson-isendpro.pdf

That's it.