Once upon a time, the average-sized American religious congregation had two telephones that really mattered.

There was the office telephone, answered by a secretary or receptionist during business hours. It was the job of this gatekeeper -- who over time became an expert on life in the flock -- to tell the shepherd which calls were urgent and which could wait.

The other telephone was at the pastor's home. Many people knew that number, but they also knew it was not business as usual to dial it.

"People knew they never should call the pastor's home number unless it was a real emergency," said the Rev. Karl Vaters, of Cornerstone Christian Fellowship in Fountain Valley, Calif. "There was a boundary there and people tried to help protect the pastor's time at home. That boundary was there to help protect his family and his ministry."

These days, both of those telephones, for all practical purposes, have been replaced by cellphones for the pastors and members of small congregations -- usually defined as those with under 200 people attending the main worship service. For most clergy, the cellphones in their pockets are always there, always vibrating to remind them of cares and concerns that rarely, if ever, go away.

It was the one-two punch of cellphones and email that first pulled clergy into the social-media age, followed by digital newsletters, Facebook pages and constantly changing congregational websites. Even in small churches, the work of the "church secretary" has evolved, from answering the office telephone and preparing an ink-on-paper newsletter to serving as an all-purpose online networker.

"The old boundaries are vanishing and, for pastors in some parts of the country, they're almost completely gone," said Vaters, reached by telephone. "That mobile phone is always with you. … Once your church passes 200 members you have to manage things in a different way. You just can't afford to be as accessible to all those church members all of the time."

So what happens today when a member of a congregation rings the pastor's cellphone? Vaters recently addressed that question in a post at Christianity Today's Pivot blog for small-church leaders. The blunt headline: "Why Most Pastors Aren't Answering Your Phone Calls."

For starters, there are too many calls to answer and about half of them are sales calls from businesses, he noted. Church members also tend to forget that many modern pastors no longer have desk telephones because they no longer have traditional offices or staffs. Many clergy -- especially in missions and new church plants -- have other full- or part-time jobs to help them pay the bills.

Meanwhile, some clergy are proactive and use text messages and emails to arrange personal meetings in "third places," such as coffee shops. They try to work calls into their time-management plans, reaching as many people as possible.

"The irony is that those face-to-face meetings are often interrupted by telephone calls," said Vaters. "So what are you supposed to do, take that call when you're actually praying with someone?"

But there are other reasons for pastors not reach for that mobile phone. Some laypeople need to learn that "some things can wait," he said. Then there was this angle in his commentary: "It's not you, it's us (except when it's you)."

Most of the time, pastors are not ignoring calls, "but sometimes we are. Let's face it, some people are a drain on resources," wrote Vaters. "It doesn't mean we don't love and care for them. … This is not a typical reason for a slow response from a pastor. But it can be a valid one."

Then there's one more thing. "Some pastors are lazy and rude," he added. These shepherds need to realize that -- one way or another -- members of their flocks deserve responses when they try to reach them. Even calling back to tell them "no" is better than leaving them feeling ignored.

Church members should know "that he's not ignoring me, he's not being mean to me," said Vaters. "They have to learn that you're trying to set important boundaries. … You're trying to spend less time in some conversations that are really not all that urgent, in order to make room for the calls that really are -- that really matter."