Known issues

  1. SIP ALG is enabled by default and must be disabled to prevent intermittent issues with phone registration and call/fax failures.
  2. DHCP DNS servers must be set to efficient servers to avoid issues with phone registration on Polycom devices.
  3. DNS relay/proxying can cause the above issue as well however by default DNS relay is disabled, but if it was turned on it must be disabled.
  4. The router's UDP time out feature can interfere with the Keep-Alive packets sent by the phones to maintain a connection with our servers if it is set to a low value.
  5. This router is capable of QoS configuration, but it has not been rigorously tested for its efficacy.
  6. This router has a high level of configurability however the configurations suggested below are the bare minimum requirements that have proven to be effective.

Resolution

  1. Log into the router
  2. Go to Firewall / ACLs > ALG Settings
    • Disable (uncheck) SIP ALG
    • SIP proxy settings are not necessary since all of the devices that Intermedia provides are preconfigured with the correct SIP credentials.
    • Save
  3. Go to Firewall / ACLs > Basic Setup
    • Change the default UDP timeout to 5 minutes
  4. The following is needed only if you have Polycom phones:
  5. Click on Hostname / DNS and modify the DNS settings:
    • Primary DNS 8.8.8.8
    • Secondary DNS 8.8.4.4
    • Ensure DNS proxying (DNS relay) is disabled (unchecked)
  6. Optional. The QoS engine on this router has not been rigorously tested. If you'd like assistance setting this up contact Intermedia for assistance.
    • The following Telnet commands were found to be useful in one implementation where RTP was tagged with DSCP value 46:
      • qos map VoIPMap 100
      • match ip rtp 30000 50000 all (Hosted PBX 2.0)
      • match ip rtp 35000 65000 all (Hosted PBX 1.0)
      • match dscp 46
      • priority percent 80