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Voice SDKs Network Connectivity Requirements



The Twilio Client JavaScript SDK has been renamed to Twilio Voice JavaScript SDK.

The following article outlines Twilio's Voice SDKs' requirements for network connectivity. It lists the Twilio servers' ports and IP addresses that the SDKs must be able to reach, and the bandwidth required for quality audio.
Twilio's Voice SDKs assume a well-performing and accessible network; problems with firewall configurations, quality of service implementations, bandwidth allocations, and ISP performance are outside the scope of things Twilio can assist with and we will need to defer to your local IT, ISP, and hardware vendors for assistance.

Connectivity checklist

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  1. Choose the edge you will connect to and allow Media servers and Signalling servers .
  2. If you are using Global Low Latency edge, check the requirements .
  3. If you have access to Private Interconnect(link takes you to an external page) edges, you will need to allow these destinations .
  4. Ensure you meet the bandwidth requirements .
  5. Check the recommendations and best practices .
  6. Test your connectivity using this Network Test Tool(link takes you to an external page) .

Applications using Twilio's Voice SDKs require connectivity to Twilio's infrastructure to be able to place and receive calls. As shown in the diagram below, two types of connections are required: Signalling and Media.

The signalling connection is a secure TLS connection that is used for sending and receiving control information to set up calls.

The media connection is a secure SRTP (Secure Real-time Transport Protocol) connection that is used to send and receive audio.

Twilio Voice SDK Connectivity.

Twilio's Programmable Voice infrastructure is deployed in edges all over the world. By default, the SDKs use Global Low Latency (GLL) to determine the optimal Twilio edge to connect to.

Twilio Voice SDK Edge Locations.

In a typical organization network setup, a firewall is used to protect the private network hosts from the Internet. Firewalls are configured with rules to block or allow traffic to and from Internet destinations based on direction, protocol, and IP address.

Twilio Voice SDK Private Edge Locations.

To access Twilio, your firewall should allow outgoing TCP and UDP traffic from your applications to Twilio's infrastructure and allow return traffic in response. Twilio will never initiate a connection to the SDK applications. Therefore, the firewall should not allow externally initiated connections back into the network.

In the Connectivity Requirements sections that follow, the required destination IP addresses and ports are listed. Your firewall should be configured to allow connectivity to the Media Servers and the Signalling Gateways corresponding to the SDK you are using.

Voice Media Server connectivity requirements

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Public Connections - Global Media IP Range

The Public Connections Destination IP Ranges and Port Ranges are now identical across all locations:

Secure Media (ICE/STUN/SRTP) Edge LocationsProtocolSource IPSource Port †Destination IP RangesDestination Port Range
sydney (au1 )

sao-paulo (br1 )

dublin (ie1 )

frankfurt (de1 )

tokyo (jp1 )

singapore (sg1 )

ashburn (us1 )

umatilla (us2 )

roaming (gll )
UDPANYANY168.86.128.0/1810,000 - 60,000

† The SDK will select any available port from the ephemeral range. On most machines, this means the port range 1,024 to 65,535.

Signalling connectivity requirements

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Signalling requirements differ between the Voice JavaScript SDK and the Mobile SDKs. This section provides the connectivity requirements for each of these SDKs.

Your IntranetAllowed destinations
ProtocolSource IPSource Port †Destination*Destination Port
Voice JavaScript SDK
Secure TLS connection to Twilio signalling** voice-js.roaming.twilio.com443
Secure TLS Connection to Twilio Regional Signalling gatewaysTCPANYANYchunderw-vpc-gll-{region}* {Where region is one of: au1, br1, de1, ie1, jp1, sg1, us1, us2} voice-js.{edge-location} {Where edge-location is one of: ashburn, umatilla, sao-paulo, frankfurt, dublin, sydney, singapore, tokyo}443
Secure TLS Insights logging gatewayTCPANYANYeventgw.twilio.com443
Mobile Voice SDKs
Secure TLS connection to Twilio GLL Signalling GatewayTCPANYANYchunderm.gll.twilio.com443 (10194 §)
Secure TLS Connection to Twilio Regional Signalling GatewaysTCPANYANYchunderm.{region} {Where region is one of: au1, br1, de1, ie1, jp1, sg1, us1, us2}443 (10194 §)
Secure TLS to Insights GatewayTCPANYANYeventgw.twilio.com443
Secure TLS to Registration ServerTCPANYANYers.twilio.com443

† The client will select any available port from the ephemeral range. On most machines, this means the port range 1,024 to 65,535.

§ Mobile SDKs versions prior to 3.x require port 10194 instead of 443. If still using pre 3.x version, we recommend you upgrade to the latest version

* Destination names starting with "chunderw" is only used by Voice JavaScript SDK versions older than 2.3.0.

Private Interconnect edge locations

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If you have access to private Interconnect connections(link takes you to an external page), you will also be able to use one of the following values:

Your IntranetAllowed destinations
Edge LocationProtocolSource IPSource Port †DestinationDestination Port
ashburn-ix (us1-ix)TCPANYANY208.78.112.0/25443
san-jose-ix (us2-ix)TCPANYANY67.213.136.0/25443
london-ix (ie1-ix)TCPANYANY185.187.132.0/25
frankfurt-ix (de1-ix)TCPANYANY185.194.136.0/25443
singapore-ix (sg1-ix)**TCPANYANY103.75.151.0/25443
tokyo-ix (jp1-ix)**TCPANYANY103.144.142.0/25443
sydney-ix (au1-ix)**TCPANYANY103.146.214.0/25443

† The client will select any available port from the ephemeral range. On most machines, this means the port range 1,024 to 65,535.

** Requires Voice JavaScript SDK 1.9.5+.

Network bandwidth requirements

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The following table lists the network requirements to deliver reasonable audio quality.

Bandwidth (Uplink/Downlink)Opus*: 40kbps / 40kbps PCMU: 100kbps / 100kbps
Latency (RTT)< 200ms
Jitter< 30ms
Packet Loss< 3%

* Opus codec is available from Voice JavaScript SDK version 1.7 and Mobile Voice SDKs 3.x

The Opus bandwidth requirements listed above are the default settings for Opus. Opus codec supports bandwidth control by allowing you to specify how much bandwidth it should use. See section recommendations and best practices below for how to configure Opus bandwidth requirements.

Global Low Latency requirements

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GLL is an AWS Route53(link takes you to an external page) feature that resolves a hostname to the edge location with the least latency. This removes the need for the application developer to determine where the end user is connecting from or manually choosing which edge to connect to.

However, in order for GLL to give accurate results, the intermediate DNS must:



If the intermediate DNS does not support RFC 7871 and the upstream DNS IP address is an Anycast address, e.g.,, then there is no guarantee Route53 will accurately determine the best edge to connect to.

How to determine if GLL will work

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To determine if your DNS supports GLL, use the dig or nslookup utilities as follows:

dig TXT

nslookup -type=txt

A DNS server that supports this RFC will have ecs set to True and contains an ecs_payload object:

_10 30 IN TXT "{'ecs_payload':{'family':'1','optcode':'0x08','cc':'US','ip':'','mask':'24','scope':'0'},'ecs':'True','ts':'1588973397.05','recursive':{'cc':'US','srcip':'','sport':'11807'}}"

A server that does not support this RFC will have ecs set to False:

_10 0 IN TXT "{'ecs':'False','ts':'1588973475.23','recursive':{'cc':'US','srcip':'','sport':'54989'}}"

Recommendations and best practices

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Use a specific edge location

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If you have a restrictive network and you specify GLL when connecting to Twilio, all media server IP addresses in all edge locations must be allowed. If you are not operating in all edges, we recommend you specify the edge that is closest to your deployment. With this approach, you will only need to allow the Media server addresses for the edge that you specify.

To select the edge, use the following snippet:


const device = new Twilio.Device(token, { edge: 'ashburn'});
const device = new Twilio.Device(token);
device.updateOptions({ edge: 'ashburn' });
// Prior to v2.0, device.setup(token, { edge: 'ashburn' })
// was used. As of v2.0, device.setup() is deprecated.
// Prior to v1.11 the region parameter was used.
// region is now deprecated, use edge
Twilio.Device.setup(token, { region: 'us1'});

Use Twilio's Network Traversal Service (NTS) when UDP ports are disallowed

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For best audio quality, your firewall should allow your local hosts to initiate the connection to twilio and send UDP (DTLS/SRTP) traffic to the Twilio Media servers.

However, If your network policy prohibits UDP connectivity, you can utilise Twilio's Global Network Traversal Service (NTS) to establish media connectivity over TCP or TLS. Please refer to the NTS documentation for a list of TURN servers and ports that will also need to be allowed.

Note, using TURN incurs extra charges as per NTS pricing. Refer to Global Network Traversal Service for more information.

Use the Opus codec to control bandwidth requirements

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The Opus codec has many advantages over PCMU and should be used by your applications. Opus is the default codec for Mobile SDKs.

To use Opus in your web application, use the following snippet when either instantiating the Twilio.Device or updating the Twilio.Device's options with .updateOptions(options):

const device = new Twilio.Device(token, { codecPreferences: ['opus', 'pcmu']});
// or
const device = new Twilio.Device(token);
device.updateOptions({ codecPreferences: ['opus', 'pcmu']});

To set a custom bandwidth (16kbps), use the following snippet:

const device = new Twilio.Device(token, { codecPreferences: ['opus', 'pcmu'], maxAverageBitrate: 16000} );
// or
const device = new Twilio.Device(token);
device.updateOptions({ codecPreferences: ['opus', 'pcmu'], maxAverageBitrate: 16000});

Use Twilio's Private Interconnect for enhanced security and bandwidth control

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Twilio offers several solutions for private and secure connectivity to Twilio. See The Twilio Interconnect page(link takes you to an external page) for more details.

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