If you call the White House comments line, you get a recording saying this (video screengrab of the recording below).
“Thank you for calling the White House. Unfortunately, we cannot answer your call today because congressional Democrats are holding government funding, including funding for our troops and other national security priorities, hostage to an unrelated immigration debate. Due to this obstruction, the government is shut down.”
The number to the White House comments line is (202) 456-1111.
Read more about the shutdown here: Lindsey Graham Goes Rogue, Blames White House For Shutdown