A common reason that there is a mismatch in the Email address as entered in RingCentral and the full UPN in Microsoft Azure.
And this IS case sensitive down to the character.
Lisa.Johnson@Bridgeoc.com is NOT the same as lisa.johnson@bridgeoc.com. They must match exactly, as this is how we tie the systems together.
Example: Our example operator is Lisa Johnson
RingCentral

Microsoft Azure AD

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