Păi atunci, încearcă:

SELECT prefix, SUM(nr) AS total
FROM (

select rtrim(rtrim(prefix)+rtrim(tel)) as prefix, count(*) as nr from dbo.tabel where (conditie = 'ceva')
and (prefix like '08%') and
(year(created)=2000 )
group by rtrim(rtrim(prefix)+rtrim(tel))
having count(*)<=100

) t
GROUP BY prefix
ORDER BY prefix, total

Nu merge aşa?

Răzvan