Just adding a response to a Teams conversation may not be enough. While some Teams members choose to be to notified on all channel activity, you cannot assume all have done so.
To call someone's attention in a channel conversation or a chat, @mention them. Type @ before their name and then select them from the menu that appears.
They receive a notification, which they can click to go directly into the point in the conversation where they were mentioned.

To get the attention of an entire team, try one of these:
- Type @team to message everyone on that team.
- Type @channel to notify everyone who has favorited that channel.
- Tag members and @mention the tags.