Dear Jasmin
Thank you very much for your helpful answer. Can you please check the short code for the phone number, you mentioned that this is: %%question_value{Question_ID}%%
That looks promising, the question ID is 16, I tried different ways to add the number to the short code, which all not worked, can you give me an example how to add the question number? I tried:
%%question_value{Question_ID_16}%%
%%question_value{Question_ID16}%%
%%question_value{16}%%
They are all not working.