LetsChat.chat, is aimed for business professionals that want to chat with others outside their organization, without having to share their phone number.
A good example would a business professional dealing with salespeople. Clearly chatting rather than emailing moves the process at a faster pace, but it involves sharing cellphone numbers.
When you sign up, you get your own chat link or button. The button can be added to your emails, either in the signature or body. The link can be shared via Linkedin or other social sites.
When the recipient clicks the link you will get a notification on your cellphone, they do not have your number.
When you click on the link a browser session starts where you can communicate.
If you miss the message or you do not want to chat at that time, the person can leave a message or if you chose to activate your calendar, set up a meeting.
Yes in the settings you can set up your OOO and you will not be notified during those times.
Connect with Linkedin, you will be taken to the Settings page, where you can verify your phone number. Then copy your own personal chat link into your email signature.