we are using UC520 with telephony 4.2(0). in phone configuration, use "w" button for watching the line. 7914 doesn't show red light if someone is on the phone sometimes, not always. it has S00105000200 firmware. do I need to upgrade firmware?
type 7961 addon 1 7914
button 1c3,1,5,6,7,8,9 2:22 7w11 8w4
button 9w19 10w13 11w2 12w14
button 13w17 14w21 15w18 16w15
button 17w16 18w12 19w24 20w10