When you choice to have a pro-installer/monitoring of the alarm system YOU pay for.. It will never be fully yours.
Just keep in mind that when you take a professional to install and/or monitor your alarm system... They don't provide you with ALL the secret access codes... The "installer code" they keep it forcing you to stay with them.
Of course, they keep some codes for them only to "protect you" to do mistakes..
When
- you sell your system (house) to somebody who don't like to follow your maintenance/monitoring contracts,
- you like to add to or alter your system well think it over how you will handle that without full access. Ask them the question and find-out the consequences when you don't have ALL access codes and full property of your system without "initial" contractor authorization!