Question

What do I need to add, if I need to at all, to avoid sql injections?

public static Login GetLoginByName(string name)
{
    var context=new telephonyEntities1();

    Login t = (from l in context.Logins
               where l.login1==name
               select l).FirstOrDefault();
    return t;
}

Answer 1

Linq-to-sql uses SqlParameter to generate SQL queries, so no you do not need to do anything extra.

From Frequently Asked Questions (LINQ to SQL)

Q. How is LINQ to SQL protected from
SQL-injection attacks?

A. SQL injection has been a
significant risk for traditional SQL
queries formed by concatenating user
input. LINQ to SQL avoids such
injection by using SqlParameter in
queries. User input is turned into
parameter values. This approach
prevents malicious commands from being
used from customer input.