The statistics look sound enough, but as already mentioned, there are faults in the procedure. The report does address those error sources, but the dismissals are not always credible.
In the discussion, it is obvious that the experimenters have a number of preconcieved ideas of how telepathy works, and their dismissal of other psi effects as possible reasons for the results betray their belief system.
I would rate this report as interesting, but it is not a sound scientific experiment. Since the experimenters, by their own admission, are biased for a positive result, the experiement should have been double-blinded.
As is often seen, they try to make several experiments at the same time, varying several paramters: Familiar/unfamiliar caller, distance, and also there are changes in protocol.
A more sound protocol would be:
One telephone connection, isolated from the normal system, to rule out unrelated calls.
ALL callers use the same phone. The sequence of callers is determined a priori.
Receiver does not answer call, but simply writes down his/her guess of the caller when the phone rings.
At each test, a random sequence of callers make calls at regular time intervals, e.g. 5 minutes.
Only after completion of the test series is the recorded guesses compared to the sequence of callers.
This protocol would eliminate the fault sources, be much more effective, and cheaper.
Hans