Until June 26, you can communicate any way you wish. After that, before a contract is in place, you MUST use the video and messaging available on Upwork. There are a couple of huge threads about this in the Announcement section of the forum.
The policy change is coming in just a few days.
This is an opportunity to change the culture of Upwork freelancing in some ways that can benefit both freelancers and clients.
Let me put this out there:
After the policy change, are we required to use Upwork video/audio call tools only?
We can use ANY tools the the client would like to use. The client can create an hourly contract for consulting with the freelancer and then use any tool she wants to use. This does NOT NEED TO BE the actual project contract. Any Upwork contract can be used.
And the client can use ANY tools for communicating. Zoom. Skype. Phone. GoToMeeting. In-person meetings. Email. Discord. Slack. These are ALL allowable under Upwork TOS.
An hourly contracts can be used to talk to a freelancer for just an hour. Or a half hour. Or ten minutes. This is very flexible.
This DOES NOT COMMIT the client to anything. The client does NOT need to hire the freelancer to work on the actual project.
Project Owner: "Did you do the discovery calls for the project?"
Hiring Manager: "Yes. I did ten calls and we ended up hiring six freelancers on Upwork."
Project Owner: "And what was the cost?"
Hiring Manager: "Just $135."
Project Manager: "Sounds good. That's less than last time."
If a client wants a discovery call, I allot 30 minutes of my time FOR FREE. It's a two-sided conversation.
Ask the necessary questions to determine if YOU want to work with the client. If you feel there are red flags on this call, post-call I would tell the client you're not able to do this project.
As mentioned, after the end of June you MUST do all discovery calls using Upwork. Until then, any communication method is OK.