Python Django和老式SQL查询

我有一个模型如下：

class call_log(models.Model):
    call_from = models.CharField(max_length=200)
    call_to = models.CharField(max_length=200)
    direction = models.CharField(max_length=200)
    end_time = models.CharField(max_length=200)
    duration = models.CharField(max_length=200)
    total = models.DecimalField(max_digits=8, decimal_places=5, blank=True, default=0)
    rate = models.DecimalField(max_digits=8, decimal_places=5, blank=True, default=0)

它有（不同）号码和sip端点发出的每个单独呼叫的记录

我要运行的SQL查询是：

SELECT DISTINCT(call_from) AS start, sum(total) AS total 
FROM polls_call_log GROUP BY start;

我该如何用django写这封信

from django.db.models import Count
call_log.objects.values('call_from').annotate(Count('total'))