Voice Chat option not available

I’'m having a strange issue. I have two users both using the same version of the client 2.5.2 both with the same headset connected to their computers and both connected to the same LAN. User A will see a “Dial” option for user B, but user B does not have a “Dial” option for user A.

If user A initiates voice chat the session runs normally. Both parties can hear each other. Everything seems fine. The only issue is that user B’‘s client doesn’'t know user A is voice capable.

Could anyone give me some feedback on this?