I have a bcm 400 connected to a very vanilla Valcom paging system. There are no zones, amplifiers or adjustments that I can make to the paging equipment. When I take a test set and go off hook at the valcom all speakers come on and it's good to go. When I hook it up to the phone system and initiate a page the speakers take about 10 seconds to all come on. Some come on right away others take longer and pages get missed. Any ideas why the speakers don't come up simultaneously?