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Quality call issues

Tudor Deak avatar
Written by Tudor Deak
Updated over a week ago


The quality of a Voice over IP (VoIP) client call is heavily dependent on the environment that call is running in. From the device the client is running on, to the network characteristics and firewall/router configuration – a successful VoIP deployment requires careful consideration of the end to end experience. This document is intended to share the best practices in configuring and selecting the best environment for VoIP calling over unmanaged networks using smrtPhone.

Firewall Configuration

Ports and Network Connectivity Requirements

Please refer to this FAQ for necessary requirements regarding your network configuration, including ports, bandwidth and firewall configuration.

Additionally, in order to check your overall firewall and port configuration, we recommend:

IP Whitelisting

You can find a fixed range of IP addresses in the provider's network which signaling and media will come from in our Twilio Client Regions documentation.


If your router includes SIP Application Level Gateway (ALG) function or Stateful Packet Inspection (SPI), disable both these functions.

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