Find Out How and Why
In order to prevent escaping, it’s important to find out why and how your dog is escaping. There are a number of options for recording a dog while you aren’t home: Video cameras (D-Link), apps (Dog Monitor) that stream live onto your smart phone, iPad recording.
If appropriate have a talk with your neighbours if they notice when and how your dog escapes. Escaping is a learned and self-rewarding behaviour and gets worse the more a dog practices it. In fact dogs can get better at it each time they escape (e.g. increasing the fence height can force a dog to get better!). Like any unwanted behaviour, you need to prevent the behaviour from occurring, teach and redirect your dog to a more desired behaviour, and reward the desired behaviour highly.
Prevention - Keeping Your Dog Safe
Short-Term Solutions
Your dog needs somewhere to feel safe, particularly if they escape due to fear. Crating - is only a short term confinement option (4 hours or less). Your dog must be taught to be comfortable in a crate first.
Denning - e.g. laundry, garage, under the house, sectioned off area in the house. Once again, your dog must be taught to be comfortable in the area first, before being left for long periods. Keeping your dog inside - some dogs like to be inside, away from the noises of the external environment where they feel safer.
Tethering - tethering your dog on a rope or chain should only be done under supervision. Dogs can easily get tangled and even strangle.
A Skyline may be a safer option to look at.
Longer-Term Solutions
Fencing tricks including roller bars, netting facing inwards 45 degrees and a second/double fence may deter fence scalers/climbers as they have difficulty getting access.
This is a great video from Ipswich City Council on fencing solutions for escaping dogs: Keeping Your Dog From Jumping Fences