What are some good messaging apps?

Hi, everyone What are some good messaging apps that don't ask for your phone number?
I have Facebook Messenger and Google Hangouts. I am looking for more apps that can message Groups. Thanks.

Forum: 

#1 Skype

Skype is a good one but you already have it. So try Voxer. It's an app that you can create groups with and talk to them. As far as I know, there is no phone number required, I think it's optional.

#2 kik is another one

Kik is another one that doesn't ask for your number.

They use usernames.

Unlike the other apps listed here, kik is text only.

#3 Telegram Messenger an Slack Accessibility?

How accessible is Telegram Messenger and Slack? I am looking for apps like WhatsApp but for the iPad and ones that you can sign up with your email.

#5 Re: voice only messaging

Hi,
I'm still planning to try this app out. What type of app is it? Does it only allow you to call or does it have a chat feature?