text to 85258

This is a free text service which was sent to me to show how it works and the service it provides. You can text  the word shout to 85258 , but when I do that it comes back message not delivered.The above is listed available to Id mobile. using iphone 11. Sms is turned on in settings where it says send as sms when imessage is unavailable. so should not have to turn off imessage if that had anyting to do wit it

I know it is a working service so not sure why it will not work on phone. Have tried turning off & on