Q. Some people talk a lot during services. Surely this is not allowed?
True, in an emergency there are certain points in the service when one may interrupt or be interrupted, and at certain places, e.g. during the P’sukei D’Zimra (preliminary Psalms) one may respond to Kaddish or the K’dushah. But the general principle is that one must not allow the outside world to intrude upon one’s worship.
I know there are some so-called worshippers who find concentration so difficult that they just have to turn to their neighbours and start a conversation, and they get quite annoyed to find that their neighbour is actually davening. If only they would realise that the prayer agenda is dealing with really serious matters of life and death, and interrupting a person who is praying may quite literally be placing their life at risk.