Add letters to dialpad in chat_control.ui
problem
There are no A-Z letters.
analysis
In case someone is publishing his/her number, which sometimes would be easier to remember.
A fictional proxy xmpp:1866xxxxxxx@tollfree.gajim.org
enhancement recommendation
Add letters.
From Ekiga:
[ 1 ] [2 abc] [3 def]
[5 ghi] [6 jkl] [7 ]mno
[7 pqrs] [8 tuv] [9 wxyz]
[ * ] [ 0 ] [ # ]