My phone is not accepting or able to make outbound calls


  • My polycom phone is indicating the line is not available (red mark instead of green) on the VVX400 or higher.
  • Yet the phone is showing as registered in PISTON.
  • The PISTON registration source port is below 1024.



  1. Assuming there is network connectivity to Voxter's hosted PBX servers, then the cause of this behaviour is related to the firewall/router having SIP ALG enabled.  Please login to the router and disable SIP ALG.  Rebooting the affected phone may be required. 
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