Phone delay on transferring calls

[mk81596]

When we try to transfer calls we "sometimes" get a delay in dialing the number on the phone. So when the user hits transer 334, there is a delay on the screen of the phone the three will come up then a couple seconds the next 3 shows up on the display and then the 4 then goes through. Just wondering if it is just a glitch or if there is a fix
Thanks,