I switch between celcom and maxis sim regularly. Been testing out celcom and there are many occasions where it says Im connected to 3G, but I cant stream any music or browse the internet. Then, when I turn to airplane mode and switch back on cellular, it shows 3G again, but I still cant use any internet. I have a feeling they have problems with poor handover issues. This happens a lot when the signals are mixed for lte and 3g, causing frequent hopping. Never had such problems with maxis. I still feel Maxis is reliable as of now.