I got a call from one of my users stating that he cannot receive outside calls. He can make internal and external calls, receive internal calls but cannot receive external calls. After verifying this I found that this is the case for about 19 other lines. When I check the line 0300 is in the public number field, when I try to change it to 5001 I get an error "'5001' is not a valid option for 'Public number'" . I have gone through line by line and have found 5001 being used in no other place as well as the other 18 numbers.