MATH PUZZLE: Can you replace...

A man in Topeka, Kansas decided to write a book about churches around the country. He started by flying to San Francisco and worked east from there. Going to a very large church, he began taking photographs and notes. He spotted a golden telephone on the vestibule wall and was intrigued by a sign which read: "$10,000 a minute." Seeking out the Pastor he asked about the phone and the sign. The Pastor explained that the golden phone was, in fact, a direct line to Heaven and if he paid the price he could talk directly to God. The man thanked the Pastor and continued on his way. As he continued to visit churches in Seattle, San Diego, Chicago, Greensboro, Tampa and all around the United States, he found more phones with the same sign and got the same answer from each Pastor.
Finally, he arrived in Texas. Upon entering a church in Dallas, behold, he saw the usual golden telephone. But THIS time, the sign read: "Calls: 35 cents." Fascinated, he asked to talk to the Pastor.
"Reverend, I have been in cities all across the country and in each church I have found this golden telephone. I have been told it is a direct line to Heaven and that I could talk to God, but, in the other churches the cost was $10,000 a minute. Your sign reads 35 cents. Why?"
The Pastor, smiling benignly, replied, "Son, you're in Texas now... It's a local call."