So, regarding call merging, there is no way to know if the carrier supports that feature via ofono, therefore we can't disable the merge button. We can however leave the button always enabled and whenever the user tries to merge calls we inform about a possible failure.
So, regarding call merging, there is no way to know if the carrier supports that feature via ofono, therefore we can't disable the merge button. We can however leave the button always enabled and whenever the user tries to merge calls we inform about a possible failure.