I joined 20 other sites (out of the many) and even with 1 rep was able to post in any of the chatrooms.
For example:
In ELL, I have just 1 rep and have posted messages in its chat. ell.stackexchange.com/users/18923/lamart
This seems like a bug because I should have needed 20 rep to post.
EDIT:
From https://meta.stackexchange.com/questions/174189/editing-a-question-answer-in-a-review-is-getting-doubled-if-you-click-the-browse, I got the idea to make this edit.
To reproduce this bug/error:
- Create a new SE account.
- Use it to make an account here. You will get 1 default rep.
- Choose a random SE site and use this account to get 1 rep on that random site.
- Repeat the above step 20 times.
- Now you have 1 rep on 20 network sites but the net SE rep is 20.
- Go to the ELL chat and ping me. (important step)
From my comment:
I have now got 40 rep since people voted this question up. Initially I had net 20 rep gained by creating 20 accounts on 20 different SE sites. Those default 1rep added up to get me to 20rep and I was able to chat. The link says one needs 20 rep in any of the SE site to chat in "all the other" category chatrooms..... but I did not have 20 rep on ELL at that moment.