A dialog or toast that doesn't time out with congratulations for making the first call. Work with team to determine messaging that is both supportive and professional. Some options could be:
"Your voice was heard. Most congressional offices log every call. Thanks for speaking up."
"You have made your voice heard"
"You have added your voice to the N calls about this issue"
We could also show different messaging depending on if it was VM, Unavailable or Contact.