Call Trees - an interesting idea...one that's been used in various forms and fashions for years. Under the right circumstances it may even work (in small organizations that is). More often than not, expectations far outweigh the actual probability of success. In fact, in my 25 + years of Crisis Management experience I have never seen a manual ‘call tree' even come close to being effective in a real crisis situation.
Call trees arose from the need to communicate information or instructions to relatively large numbers of people as quickly as possible, typically in an emergency or crisis situation. The premise is that emergency has prevented access to your facility or happens to occur when your employees are not at work.
Let's assume you must reach 2,000 employees with a single SHORT message. Now, to start the ball rolling, you simply ask one person to call two more people and deliver the message. Those two people would call two more people; those four people would then call eight people and so on, until you've reached all 2,000 people that must receive the message. Simple and effective - as long as the planets are aligned, you're unbelievably lucky and every one of your employees is at home waiting for a call they are not expecting! Bottom-line, the process simply will not work - ever, but it sure looks good on a diagram!
The number one reason for failure is the 100% probability that the call-links will be broken and that all corresponding call-chains will come to a grinding halt. Not reaching one person could end your ability to reach 50% of your people. Now think about reaching 2,000 people on a beautiful Saturday afternoon on a long weekend; your probability of success is zero. It can literally take days to successfully reach everyone on the list. This coupled with the headaches associated with maintaining accurate contact information make call trees a very ineffective tool for emergency notification.
Most call trees have people's home phone number, with the assumption they're always reachable. Some add a cell phone, but rarely do they go past two devices. Other than members of your Crisis and Emergency Management Teams, employees are not waiting around to receive company calls on a weekend.
Experience has shown that when you are conducting unscheduled calls, it will average at least 3 attempts per person to make contact and it could be as high as 6. Lots of questions come to mind, such as: how long do you wait between calls, do you attempt to find others to make additional calls; do you leave a message and assume that person will eventually make his or her calls, how do you verify that they did, do you have people call you back? There is a consequence to every one of these questions; the answers to which will always lower the probability of success.
When you are physically calling someone to provide information and instructions, you will always exceed the projected time it takes to complete the call. People will have questions and interestingly enough, the more senior the person you're calling, the longer the call will take.
Experience has shown that when a message is verbally passed on from person to person, the message itself begins to change on the third repeat and by the sixth repeat; the message may not even resemble the original. In reaching 2,000 people in our scenario, the message would need to be repeated perfectly 2000 times by 1,022 people calling out.
I don't know about you, but I sure wouldn't want to bet my company's survival on 1,022 people accurately relaying a message in a short time frame. In fact, the use of manual call trees (versus the use of automated tools such as ERMS Messenger) would never pass as an effective means to mitigate the intended risk.
For the record, to reach 2,000 employees using a manual call tree there will be 11 call levels, 1,022 people repeating the message -- it will require roughly between 6,000 and 12,000 actual calls and take anywhere from 10,000 to 34,000 minutes based on call lengths of 3 to 12 minutes and call attempts of 1 minute. That's 167 to 567 hours of effort to complete and the time spent by the people receiving the message isn't even included in these numbers. And it can get much worse.
By comparison, ERMS Advantage Services requires no manual effort and can make 2,000 calls in just an hour or two including time between re-dials. It's worth a look!