Outcalling to pagers is especially diffulcult, because sometimes the paging company picks up on the first ring, sometimes the 2nd ring. Use your butt set on monitor on the 1st outside line to listen to the outcalling sequence, and determine the exact time delay needed from the end of the pager's telephone number and the beginning of the display string.

Our pager service was so poor, that my outcalling string looked like this:

9*5551212****1*1*1*1*1*1*1*1*1*1#

I would get anywhere from 1 to all 10 "1"'s in the display, depending on how long it took the service to answer.