Told in “two acts and forty-five phone calls,” Belles visits six southern sisters, who, over the course of an autumn weekend, seek to bridge the physical and emotional distance between them via the telephone, and in the process come to terms with their shattered family history. The gold standard among Mr. Dunn’s many plays about southern women, and offering very strong roles for an ensemble of six actresses, Belles continues to pack an emotional punch after all these years.