We can't set up the conversation because your organizations are not set up to talk to each other.

[KevinTParker]

I am starting a new topic here because I haven't seen anyone with this issues.

External access is turned on. This is working for other organizations. 2 organizations here can't seem to communicate.

Organization A (mine) : I have added OrgB.com and OrgC.com to our list of domains.

Organization B : They have had OrgA.com and OrgC.com to their list of domains.

Organization C : They have had OrgB.com and OrgA.com to their list of domains.

When I say 'talk' I mean, they do not get the error message in the subject. Can't talk means we get the "organizations are not set up to talk to each other".

Organization A can talk to C, but not B.

Organization B can talk to C, but not A.

Organization C can talk to B and A.

Organization A and B are "Islands". Organization C is "Teams Only". A user in Organization A is 'Team Only" Still it doesn't work.

FYI, the communication in Skype for Business works for the A and B.

[#2]

When was the user Thats teams only switched over?? If orgs are in island mode they will receive messages in Skype for business when external orgs sends messages

[#3]

@adam deltinger The messages never get through, only the 'not set up to talk to each other'. Its like Microsoft (or something) has a hand between the two organizations and say, 'you can't talk' no matter how you have it set up.

[#4]

Is Skype running on the users in island mode?

[#5]

@adam deltinger Yes.

[#6]

I think we've got it narrowed down a bit. Was successful with my testing once added to exclusion list. Think it's related to islands mode and end points. Anyway, report back to this post after that vid, and checking settings and setup on the other org, since other post was kind of hijacked :).

[#7]

@KevinTParker 

Hi,

I'm not sure if this is helpful to anybody who's still having this issue around. Since last week I have been receiving complaints about this exact issue from one of our clients and I don't see many articles on the internet, let alone a concrete solution for this issue. Below given is the issue screenshot our client have sent us.

Actual Issue

Anyhow, I was just having a look at our client's tenant configuration using PowerShell because going to https://admin.teams.microsoft.com/ > Org Wide Settings > External Access / Guest Access doesn't help at all.

I came across this interesting finding:

Verifying Tenant Federation Settings

Why the above finding was interesting, because both on the Teams Admin Center and SfB Legacy Portal we did not block or allow any domains at all. It's open federation, therefore we should not have any domains listed under AllowedDomains parameter above.

I had to go to Skype for Business Legacy Admin portal > Organization > External Communications > External Access = On except for blocked domains. Give it some 10-15 mins, you will be able to chat and view free/busy info with External Users now.

After I made this change, ran the same command to verify the federation settings. This is how it has changed now.

Stay Home, Stay Safe. Utilize lockdown days for your family :)

Thanks,

Naveen

[#8]

@Naveen_Kishore This is great information - thanks for putting it together. I've been encountering this issue for quite a while now and am wanting to have correspondence over Teams with more and more colleagues, but am unable to. I want to bring this to our IT team as a request, but do you know if there are any security implications to this?