Teams external messages not connecting - connecting with Skype

[JCapozzi]

I have an annoying problem, which prevents me from communicating with my clients: 

1. I look for an external user from my Teams client.

2. The chat initially comes up with the correct person, but at the bottom says something like "due to org policy changes, certain functions are no longer allowed, click here to switch" and it switches to the external user's address with a skype logo on it.

3. The message i then send to that user says "This user is unavailable or offline. We've sent an email instead." I know that this user can communicate correctly and is online, but my messages never get through.

4. My organization is set for Teams only.

Can you tell me what i'm doing wrong? Communications with a different client go through correctly - not with a skype logo. Is this a setting i need to update or have the external client update?

[#2]

@JCapozzi Hello, organizations can have different settings which will affect how and if it will work. I recommend these two articles for guidance as how your own and the other organizations settings should be set up for federated (external) chat to function.

Manage external access (federation) - Microsoft Teams | Microsoft Docs

https://docs.microsoft.com/en-us/microsoftteams/coexistence-chat-calls-presence