Celcom was a pioneer for mobile phone technology and I heard they have one of the best coverage. Before I switched to Maxis some 20 years ago, I was using Celcom analogue mobile system. Nope, not the Motorola "brick" phone thankfully! It was the Microtac or something named like this from Motorola. Then came Maxis with their GSM system, and my friend persuaded me to change to Maxis and I have been with Maxis ever since.
I have never considered any other mobile telephone operator until now when I could not get any decent mobile signal strength from Maxis after moving to a new house. I recalled the previous owner was using Celcom line so I thought perhaps that telco should be getting good signal.