Comparing apples with oranges phone coverage style

So Aaron bought the new Aldi mobile phone SIM offering, happy in the knowledge that it came with Telstra 3G coverage.

Hmmmm, well on our drive we discovered not. Sam's phone (green case) has Telstra coverage (purchased direct from Telstra) and Aaron's has Telstra coverage purchased through Aldi. 

I had bars and Aaron had on SOS. 

Hmmmmmmmmm, not happy!  Don't fall into the same trap!