Integrating with telephone systems (PSTN)

You may wish to enable standard PSTN and mobile telephones to dial in to your Pexip Infinity deployment. This allows callers using these devices to join a meeting as an audio-only participant.

To do this, you need to implement a trunk that will route your specified PSTN numbers to the aliases of your Virtual Receptions. Once in the Virtual Reception, participants can use their telephone keypad to enter the numeric alias of the Virtual Meeting Room or Virtual Auditorium they wish to join.

You can also route PSTN numbers directly to Virtual Meeting Room aliases, but this is less common because it requires a 1:1 mapping of PTSN number to VMR, whereas using a Virtual Reception means that a single PSTN number can be used to access multiple VMRs.

You can use any service but in this topic we use Twilio as an example.

Overview

The steps required to enable PSTN access to VMRs are:

Obtain one or more PSTN numbers — usually one for each country, city or other geographical location from which you want to provide telephone access.
Configure the PSTN service so that calls to each number are routed to the alias of your Pexip Infinity Virtual Reception. Depending on the service you are using, you may need to configure the Virtual Reception with one alias per PSTN number, or you might be able to route all PSTN numbers to the same alias.
Ensure that each Virtual Meeting Room and Virtual Auditorium that you want to be accessible via PSTN has a numeric alias (in addition to any other aliases it may already have).

Overview of PSTN to Pexip Infinity integration

The diagram above gives an example of how PSTN calls can be routed to Pexip Infinity.

When telephone participants call their local PSTN number, they are routed to the Pexip Infinity Virtual Reception. From there, the participants enter the numeric alias of the Virtual Meeting Room they wish to join. At the same time, participants using other standards-based endpoints, including SIP VoIP telephones, SIP/H.323 VTC endpoints and Pexip Infinity Connect clients, can access the same Virtual Meeting Rooms directly by dialing the room's URI.

Prerequisites

To enable PSTN dialing to Virtual Meeting Rooms, you must ensure that:

Every Virtual Meeting Room and Virtual Auditorium that you wish to be accessible from the Virtual Reception has a numeric alias (in addition to any other aliases it already has). For more information, see Configuring Virtual Meeting Rooms (VMRs).
You must have appropriate _sips._tcp DNS SRV records configured for the domain to be used in the alias of the Virtual Reception. In this example, we will be using the alias vrr@example.com so we need to have DNS records for _sips._tcp.example.com. for each Conferencing Node in our deployment. For more information, see DNS record examples.

Example using Twilio

In this example, we assume you have a Twilio account. Free trial accounts are available that offer limited functionality sufficient for testing integration with Pexip Infinity.

Step 1: Create a SIP trunk

From the Twilio interface, select the option to Create new SIP Trunk.
Give the trunk a name:
Go to the Origination settings and select Add new Origination URI.

In the Origination SIP URI field, enter sips: followed by the alias that you will use for your Virtual Reception.

In our example, we enter sips:vrr@example.com

Step 2: Assign PSTN numbers

Go to Numbers and select either Add an Existing Number (if you already have one configured) or Buy a Number.
Select the telephone number(s) you wish to assign, and then Add Selected.

In this example, we have set up the following PSTN numbers for our SIP trunk:

US: +1 555 456789
UK: +44 118 456789
Australia: +61 222 456789

Step 3: Create a Virtual Reception

We create a Virtual Reception and assign it the alias that we've used for the SIP trunk, as follows:

From the Pexip Infinity Administrator interface, go to Services > Virtual Receptions and select Add Virtual Reception.
Give the Virtual Reception a Name and an Alias. The Virtual Reception type should be left at the default Regular. (For more information about configuring Virtual Receptions, see Configuring Virtual Reception IVRs.) Then add each of the aliases you have already configured in Twilio:

Option	Input	Notes
Name	Toll-free Virtual Reception access from Twilio	This single Virtual Reception will be accessible globally by local toll-free numbers.
Description	Allow users to dial a local telephone number and then select a VMR.
Service options
Virtual Reception type	Regular
Aliases
Alias: #1
Alias Description	vrr@example.com SIP trunk from Twilio

Now whenever participants dial any of the PSTN numbers set up in Step 2, they will be taken to the same central Virtual Reception.

Step 4: Add numeric aliases to Virtual Meeting Rooms and Virtual Auditoriums

Next, we need to ensure that our Virtual Meeting Rooms and Virtual Auditoriums are accessible from the Virtual Reception. To do this, we add a new, unique numeric alias to each Virtual Meeting Room and Virtual Auditorium. In this example, we want participants to be able to access Alice's Virtual Meeting Room by entering 25423 on their keypad, and the All Hands Virtual Auditorium by entering 25499, so we edit these services as follows:

Alice's VMR

Option	Input	Notes
Name	Alice's VMR
Description	Alice's personal meeting room
Aliases
Alias: #1
Alias Description	meet.alice.jones@example.com URI for Alice's VMR	This is the existing alias for Alice's VMR.
Alias: #2
Alias Description	25423 Number for Alice's VMR when accessing via the Virtual Reception.	We add this new alias to the existing VMR configuration.

All Hands Virtual Auditorium

Option	Input	Notes
Name	All Hands
Description	Virtual Auditorium for All Hands conference
Aliases
Alias: #1
Alias Description	all-hands@example.com URI for All Hands conference	This is the existing alias for the All Hands conferences.
Alias: #2
Alias Description	25499 Number for All Hands when accessing via the Virtual Reception.	We add this new alias to the existing Virtual Auditorium configuration.

Joining a Virtual Meeting Room

Now Alice can tell participants to join her VMR by doing any of the following:

dialing meet.alice.jones@example.com
from the US, dialing +1 555 456789 and then entering 25423
from the UK, dialing +44 118 456789 and then entering 25423
from Australia, dialing +61 222 456789 and then entering 25423.

Likewise, participants can join an All Hands conference by doing any of the following:

dialing all-hands@example.com
from the US, dialing +1 555 456789 and then entering 25499
from the UK, dialing +44 118 456789 and then entering 25499
from Australia, dialing +61 222 456789 and then entering 25499.

So in our example, a telephone participant in the US dials +1 555 456789 and is routed to the Pexip Infinity Virtual Reception. There they hear an audio prompt asking them to enter the number they wish to connect to. They enter the numeric alias for Alice's VMR, 25499, and join the VMR as an audio-only participant.

Other participants using an Infinity Connect client see the telephone participant in the roster with a name in the format <participant's telephone number>@ptsn.twilio.com: