I have several SX200ICP's that I an adding ARS entry's for IP trunking. When I try to add a leading digit of 3 the system says it is already assigned. I can add 30, 31, 33, 34, 35, 36, 37, 38, and 39 as leading digits but not 3 or 32 or 328. if I break it down further I can add 3280 through 3289...