Then you normally cancel to the end of that term — unless a special right applies, which is what your orders may give you.
Initial terms are capped at 24 months. Once a contract has renewed, it can be cancelled at any time with one month's notice.
A price increase also opens a free exit within three months of being notified.
Check your invoice for a price change in the last three months.
If you are leaving Germany, the move-abroad route overrides the minimum term anyway.
§ 56 TKG, § 57 TKG. General information about German law, not advice on an individual case.
Then you normally cancel to the end of that term — unless a special right applies, which is what your orders may give you.