Use Wer@home but it does have a monthly fee. you get what you pay for and after finding box kits at bestbuy and self installed IP cameras too inconsistent went with a professional system. App works great, helps me control my home and not just monitor video. Gives me the ability to control heat, lights, water and the security part of it is self monitored with video that sends it to my phone if triggered or based on any of the smart rules I create. Before I had an app for my lights, one for my heat, one for video and in some cases two apps for different lights. Now it is just one app, very easy to use. The other item I like about it is it has a ZWave adapter which they made non proprietary, I can buy any ZWave device out there and it connects to this system which I did off amazon for a water valve, light switches, thermostat and door lock! Best part his instead of having 4 more apps the adapter ties them all into the one wer@home app which I like. I have smart rules set up that when I arm the system my water turns off and rules if the flood detector triggers my water turns off. Have a lot more, I went a little overboard as you own full control via the app and do not need to ask someone to set it up for you like most systems.
To comment on who calls or let's them in for an alarm. Either I am calling them through the local 911 direct access number for my area or one of 3 neighbours/friends I have setup as standard users. I can then unlock or relock my main door from where ever I am. $30 a month but I actually feel I get that and then some use out of it.