bind rshift callvote
...ez

Also i endorce using some other commands:
voice_enable 0 (disables voice chat)
hud_saytext_time 0 (Disables chat, can still view chat by pressing T)

you can also use this script to make a toggle Key Enable/Disable for chat:

Bind \ "+ChatOff"

Alias +ChatOff "hud_saytext_time 0"

Alias -ChatOff "bind \ +ChatOn"

Alias +ChatOn "hud_saytext_time 12"

Alias -ChatOn "Bind \ +ChatOff"