Some aspects of what is considered good manners have changed over the last few decades. However, the basic points of good manners when another person is talking are relatively unchanged.
Generally people feel when another person is speaking the rules are -
This means don't fidget or look all around the room. These days it also means don't use your mobile phone. In many situations it is polite to put your mobile on silent. The rules are the same whether you are in a one to one conversation, sitting in a meeting or in a large room listening to a guest speaker.
Don't talk when someone else is speaking
This means don't have a chat to the person next to you or make comments aside. It is disrespectful to the person speaking and makes it difficult for the person next to you to follow the speaker. Others in close proximity may also be distracted.
I find it annoying when the person next to me at a meeting talks when someone else has the floor. Okay, I have occasionally been guilty of making a quick relevant comment to the friend next to me but it is something I try not to do.
If you do have to take a call on your mobile because your child's school has phoned (yes, it is an emergency) move away from others so your phone conversation does not distract from the speaker.
Don't interrupt the speaker
John Locke, a physician and philosopher born in 1632 said, 'There cannot be greater rudeness than to interrupt another in the current of his discourse.'
If you are attending a public address the speaker usually says there will be an opportunity for questions at the end. On occasions he/she will say questions are welcome during the talk. These instructions need to be followed.
When you are engaged in conversation with one other person or a small group it is polite to take turns to speak. One person should speak at a time. Sometimes discussion gets heated and people tend to interrupt each other in their enthusiasm to put forward their view. Friends are usually forgiving of this as it can be part and parcel of an interesting discussion. I guess it's just important to avoid interrupting or talking over another person too much.
Sometimes one person is doing just about all the talking and doesn't give others the chance to have their say. This shows a lack of consideration and is also bad manners. However, among friends there are occasions when one understands another person's need to vent. As long as the friend gives you the opportunity to let off steam when you are stressed or upset, you probably don't mind.
Show an interest in what the speaker is saying
If you are in a one to one conversation, this could mean maintaining eye contact, but without staring and making the person uncomfortable. You might nod occasionally, say 'Yes' or make a sound that shows you are following what the person is saying. A few relevant questions show you are listening. These are all techniques known as 'active listening.'
In a group situation you need to look at the speaker and avoid fidgetting. A relevant question asked at the appropriate time shows you are interested.
Don't walk away before the speaker has finished
Okay, you are unlikely to wander off in the middle of a friend talking to you in a one on one situation. If you are part of a small group and you need to be elsewhere, a quick comment that you need to go is more polite than simply wandering off and having people wander if you were offended, unwell or just bored. Try to wait for a break in conversation so you aren't interrupting someone.
Don't hang up without saying goodbye
Do I need to say if you are on the phone don't simply hang up without saying goodbye? It can be tricky to end a conversation if the other party is wound up and hardly stopping to take a breath. However, sometimes one cannot spend any longer on the phone due to an appointment or the need to pick up children from school. Sometimes you need to cook tea or attend to something with high priority.
The preceding are rules I was brought up with and I feel awkward about breaking them. I have found if I am on the phone and there is an automated voice telling me it is okay to punch in numbers before the message is finished, I am hesitant to do so. Somehow it seems disrespectful. Feel free to have a laugh as it is an electronic message, not a human speaker with feelings.
I also feel 'wrong' about hanging up mid message. The automated voice may have told me I can 'simply hang up,' once my business is complete. I still feel I should say, Thank you, ' or 'Goodbye.' I sometimes wonder if anyone else feels this way or if it is just a personal quirk.
When we are talking we like to know other people are listening to us. In turn others feel positive when they know they are being listened to. After all, what is the point of talking if no one is paying attention? Sometimes the best way you can help someone is to just let them know you are listening to them.