Are security systems efficient if you don’t have a landline connection at home?
There are differing opinions on that. The best systems have a redundancy algorithm that switches to a dedicated cellular network in the event your primary home line goes dead. Look for that. It is a good setup, because for the most part your typical security traffic is carried by solid copper cable or even better, new fiber optic VOIP networks.
Efficient? How can having a phone line affect efficiency?