asp.net - passing an array value to querystring

Question

This is a bit of a problem that I have. I store some value into an array:

   Telco1 = a.Split(";")

    For i = 0 To Telco1.Count - 1
        Telco2 = Telco1(i).Split(".")
        TelcoID.Add(Telco2(0))
        TelcoName.Add(Telco2(1))
    Next

Telco1 and Telco2 is Public Telco1() as String. When the user choose an TelcoID that was stored into the TelcoID array, I want that value sent to another page:

Response.Redirect("ReloadValue.aspx?TelcoID=" + TelcoID[0])

Currently the error said

Operator + is not defined for string and System.Collection.Arraylist

Then I try to send the value over as a predefined integer like this:

Response.Redirect("Product.aspx?TelcoID=" + "2")

At the next page("Product.aspx"),

b = Request.QueryString["TelcoID"].ToString()

but the error that I receive states that

value of type System.Collection.Specialized.NameValueCollection cannot be converted to string

I wanted to used that value that was over to this page to be used to determined the data that I wanted to get from the database to shoe in the dropdown list. May I know how do I rectify this error?