Actually It's Commander Tartar's Theme

Actually it's Commander Tartar's Theme is a song from the Octo Expansion.

Description
This song is played in a cutscene where the Telephone introduces itself as Commander Tartar and declares its plan to destroy and recreate all life on Earth with the NILS Statue.

The song is a heavily distorted version of Telephone's Theme, starting as normal (albeit with breaks every two beats), but then slows down and distorts on the third loop. Then, slowed-down demonic noises play alongside said distorted vocal.

In-game, there's an extra part that's not heard on the Octotune version, consisting of repeated vocal intro and percussions. This part plays as the NILS Statue opens its mouth to reveal its cannon.