gistfile1.cs

var order = allCalls.Select((number, index) => new
	{
		Number = number,
		Duration = allDuration[index]
	})
	.GroupBy(x => x.Number)
	.Select(x => new
	{
		Number = x.Key,
		Count = x.Count(),
		Duration = x.Sum(c => c.Duration)
	});