Try :
case callrecord_contacttype
when 1 then 'Routed voice'
when 2 then 'Direct incoming voice'
when 3 then 'Direct outgoing voice'
when 4 then 'Direct internal voice'
when 5 then 'Routed callback'
when 6 then 'Routed email'
when 7 then 'Direct outgoing email'
when 8 then 'Routed chat'
else ''
end
See http://msdn.microsoft.com/en-us/library/ms181765.aspx for syntax.