I am on that very same build.
FYI: I've had to upgrade two customers this week because 6.1 build 11.15.2603 has issues with the monitor/speed dial buttons reflecting true phone status. Which is why I went in that direction earlier.
(6.1 build 11.15.3104.0 corrects this issue.)
Is the "speed dial" being programmed via Shoreware Director IP phone button programming page?