Reach your SIP VoIP telephone using a browser now.

Make Calls Using a Browser


Modern browsers can make phone calls since 2013, while using the web-grade security unprecedented in telephony before. You can now start your own experimental frafos gateway service to inter-connect web-browsers to SIP networks. The gateway will be started off Amazon Elastic Cluster: you can launch instantly, without the IT pain of buying/integrating/maintaing equipment and it still remains your own service. You retain 100% control of its function and privacy. More than that you can deploy multiple geographic services for the globally finest experience and disaster resilience.

Modern Browsers

Currently available WebRTC-enabled browsers:

  • Firefox: version 23 and above; version 33 and above support H.264 video
  • Chrome: version 27 and above
  • Opera: version 20 above

Administrative Geography

The gateway service is independent of the SIP service it interconnects with. The gateway operator does not need necessarily to run a SIP service or serve all users of someone else's SIP service. Not even an agreement with a SIP service operator is needed, as long as a valid SIP account is set up. If the SIP service connects to the Public Switch Telephone Network (PSTN), a browser-intiated call can even reach traditional telephony users. Note that the link between browser and the WebRTC-2-SIP gateway is encrypted using web security -- unprecedent level of security in public telephony's history.

Globally Finest Experience

Measurements show that inter-continental communication over the Internet dramatically impairs quality of speech and video. With a gateway on the same continent as its user, the round-trip time stays typically within 50 ms which yields good media quality. Going across continents adds in average 120ms which has devastating impact on the call quality. The EC2-hosted Frafos WebRTC-2-SIP gateway can be deployed in multiple availability zones and use proximity routing, so that users always talk to the nearest gateway.

Requirements and Limitations

Amazon Web Services Account must be established prior to launching a trial gateway and will incur cost charged by amazon. The service is a trial and comes "as is" and "as available" with no warranties and or representations of any kind. Call duration is limited to one minute. No SIP service is provided: the gateway service connects to an existing SIP service.

End-user Prerequisits

  • SIP account: SIP URI and password. E.g. "", "secret". If you don't have a SIP service yet, you may sign up for a free SIP service. Some are listed on .
  • address of the cluster. E.g. "". This is the URL the administrator obtained after completion of cluster formation.


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Technical Details

Cluster and Auto-Scaling

There are two key technical elements: the actual "workhorse", WebRTC-2-SIP gateway, and its organization in the Amazon EC2. Starting the cluster creates a whole array of resources the administrator would have to provision manually otherwise: a group of gateway instances, a scaling plan to resize the cluster up and down (by default starting from one with maximum being four), a load-balancer and a set firewall rules. The auto-scaling conditions are triggered on achieving certain average CPU utilization thresholds for a period of several minutes. When a cluster is being scaled down, ongoing calls are not interrupted during a graceful period. When the period is over, the instances, calls on it and data on it will be terminated irrevokably.

Administrative Access

The gateway instances have administrative web-interace that can be accessed using username "sbcadmin" and password equal to Amazon instance id. You can also gain root access to Command-Line by secure-shelling to the machine using the SSH key creating when launching the instance/cluster.

User Access

Users can reach the gateway by opening an HTTP link with public IP address of the instance if launched as single instance. If started as a cluster, the load-balancer Web address appears in Cloud Formation Outputs.

Administrative Prerequisities

The administrator needs to have the following information:

Information Where to Get It Example
Amazon Web Services ID and geographic region If you do not have an account ready, go to, click Sign up and follow instructions. Part of the procedure involves receiving a verification phone call and providing payment information. The account ID can be found under "My Account". 372325483748, EU-west
AWS SSH keypair for the targetted geographic region In the EC2 Management Console under "Key Pairs" mycompany-keypair, -----BEGIN RSA PRIVATE KEY----- MIIEpAIBA...

What Next...

... once the service is started? End-users can go to its web-page with a sample Javasrcipt application, and start accessing their SIP service using a WebRTC-ready browser. Administrators can fine-tune the service:

  • create a "nicer" DNS alias for the service than the default amazon naming policy creates.
  • They can administer the cluster status by going to amazon Console at and fine-tune. For example they can align the scaling plan, or they may introduce a more restrictive firewall rule permitting incoming SIP traffic only from well-known IP addresses.
  • They can monitor monitor the service using "CloudWatch".
  • They can access administrator interface of the currently running gateway instances by going to their respective HTTPS addresses.
  • They can start another cluster in some other geographic region to establish global presence and local experience for gateway users.
  • They can find more information on the Frafos Resources site.

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