Getting items with overlapping DateTime using Linq

Have a live chat database and I am trying to get an idea of how many concurrent chats staff are taking.

I'm not sure the best way to report it so I have decided to get a list of chats for a given period then for each one display a count of chats that overlapped that one in someway.

I am querying 2 tables across a join but this is just to get the Operators name.

The fields that have the relevant dates are

DateTime? ChatRequests.Answered

DateTime? ChatRequests.Closed

I think I have everything covered, I just want to see if anyone can tell me if I'm missing anything, or if there is a better approach to it?

ChatRequests
.Where (cr => (cr.Created.AddHours (10).Date == DateTime.Now.AddDays (-1).Date))
.Where (cr => cr.OperatorID.HasValue)
.Join (
    Operators, 
    chat => chat.OperatorID.Value, 
    op => op.ID, 
    (chat, op) => 
        new  
        {
            chat = chat, 
            op = op
        }
)
.Select (
    g => 
        new  
        {
            Operator = g.op.FullName, 
            Answered = g.chat.Answered.Value.AddHours (10), 
            Closed = g.chat.Closed.Value.AddHours (10), 
            Duration = (Decimal)((g.chat.Closed.Value - g.chat.Answered.Value).TotalMinutes), 
            Company = g.chat.AccountName, 
            Contact = g.chat.ContactName, 
            OtherChatsInSamePeriod = ChatRequests
                        .Where (cr => (cr.OperatorID == g.chat.OperatorID))
                        .Where (cr => (cr.ID != g.chat.ID))
                        .Where (
                           cr =>    (cr.Answered.Value >= g.chat.Answered.Value && cr.Answered.Value <= g.chat.Closed.Value) 
                                     || (cr.Closed.Value >= g.chat.Answered.Value && cr.Closed.Value <= g.chat.Closed.Value)
                                     || (cr.Answered.Value < g.chat.Answered.Value && cr.Closed.Value > g.chat.Closed.Value)                        
            )
            .Count ()
        }
)