When I set about looking for independent data, however, to confirm the superior performance of Verizon’s network, I was astonished to discover that I had managed to get things exactly wrong. Despite the well-publicized problems in New York and San Francisco, AT&T seems to have the superior network nationwide.

And the iPhone itself may not be so great after all. Its design is contributing to performance problems.

Roger Entner, senior vice president for telecommunications research at Nielsen, said the iPhone’s “air interface,” the electronics in the phone that connect it to the cell towers, had shortcomings that “affect both voice and data.” He said that in the eyes of the consumer, “the iPhone has the nimbus of infallibility, ergo, it’s AT&T’s fault.” AT&T does not publicly defend itself because it will not criticize Apple under any circumstances, he said. AT&T and Apple both declined to comment on Mr. Entner’s assessments.