It should be right with " we have taken the cellpone", why my answer is wrong?
"Have Taken" is not right because word "taken" is a v3 (verb 3) which is should be apply for the past / already happened..
Have taken is correct as well because it is present perfect tense where the thing happened in the past but it is still ongoing right at the moment.
Pay attention to the context. This is Past Perfect Tense section.