Why does FS open ports on my FIOS router by itself?

I have been seeing SIP 503and telephone calls in ring busy

Is there a way to stop or limit FS from opening too many ports?

localhost
xxx.x.x.x    Verizon FiOS Service
Tcp Any -> 4567    All Broadband Devices    Active     
    new-host
192.168.1.xx
    Destination Ports 8022
TCP Any -> 8022    All Broadband Devices    Active   
   
    192.168.1.
    SSH
TCP Any -> 22    All Broadband Devices    Active   
   
    192.168.1.xx:5070
    FreeSWITCH
UDP Any -> 5070    All Broadband Devices    Active   
   
    192.168.1.xx:5080
    FreeSWITCH
UDP Any -> 5080    All Broadband Devices    Active   
   
    192.168.1.xx:5060
    FreeSWITCH
UDP Any -> 5060    All Broadband Devices    Active   
   
    192.168.1.xx:5070
    FreeSWITCH
TCP Any -> 5070    All Broadband Devices    Active   
   
    192.168.1.xx:5080
    FreeSWITCH
TCP Any -> 5080    All Broadband Devices    Active   
   
    192.168.1.xx:5060
    FreeSWITCH
TCP Any -> 5060    All Broadband Devices    Active   
   
    192.168.1.xx:15952
    FreeSWITCH
UDP Any -> 15952    All Broadband Devices    Active   
   
    192.168.1.xx:15953
    FreeSWITCH
UDP Any -> 15953    All Broadband Devices    Active   
   
    192.168.1.xx:11350
    FreeSWITCH
UDP Any -> 11350    All Broadband Devices    Active   
   
    192.168.1.xx:11351
    FreeSWITCH
UDP Any -> 11351    All Broadband Devices    Active   
   
    192.168.1.xx:16052
    FreeSWITCH
UDP Any -> 16052    All Broadband Devices    Active   
   
    192.168.1.xx:16053
    FreeSWITCH
UDP Any -> 16053    All Broadband Devices    Active