Texting a US number in France from the US

How do i text from the US to a US phone number that is in France?

My US friend is in France for a visit and texted me from their US T mobile number.  When I simply replied from my US T Mobile number, I do not think it was received by my friend who would normally respond.

How do I send a text to the US number that is being used in France?

Gracias