The Telstra share price is down 20% from its 52-week high, which I think is a buying opportunity for investors. This is because after years of struggles, the telco giant appears to be close to returning to growth. Especially given the early success of its T22 strategy, which is creating a much leaner operation. Combined with easing NBN headwinds and the arrival of 5G internet, I think Telstra could prove to be a great long term investment.