Registering devices to Pexip Infinity

Pexip Infinity acts as a SIP registrar and H.323 gatekeeper.

In addition to SIP and H.323 endpoints, Infinity Connect desktop clients and Infinity Connect Mobile clients for Android can also register to Pexip Infinity Conferencing Nodes. This allows Pexip Infinity to route outbound calls to those registered devices without having to go via a SIP proxy or H.323 gatekeeper, or rely on DNS.

Note that devices do not need to be registered in order to make inbound calls to Pexip Infinity.

For end-user instructions on how to register a device, see Registering your device to receive calls.

Configuration summary for enabling registrations

To configure Pexip Infinity to accept registrations and route calls to registered devices you must:

1. Ensure that the Pexip Infinity's registrar service is enabled (Service configuration > Registrar).
2. Configure the aliases that devices are allowed to register to Pexip Infinity (Service configuration > Device aliases).
3. Configure appropriate Call Routing Rules (Service configuration > Call routing). Rules are required in all cases except for when using Manual routing to add a participant to a conference.

Each step is described in more detail below, after the explanation of how Pexip Infinity manages registered devices.

How it works

Registering devices

The registrar service on Pexip Infinity is enabled by default. However, a device can only register to Pexip Infinity if the alias it wants to register has been added to Pexip Infinity's list of allowed device aliases (Service configuration > Device aliases).

Device registrations can optionally also be subject to authentication. To enforce authentication, username and password credentials must be included when the alias is added to Pexip Infinity's list of allowed device aliases. When credentials have been included, the device's registration request will be challenged and the device will only be allowed to register with that alias if it provides matching credentials. Pexip Infinity supports Digest authentication only.

A device can register to any Conferencing Node. Pexip Infinity does not apply any form of registration load balancing or failover. Multiple devices can register with the same alias.

• To register a SIP device, enter the IP address or FQDN of a local Conferencing Node as the SIP proxy.

• To register an H.323 device, enter the IP address or FQDN of a local Conferencing Node as the H.323 gatekeeper.

  All of the device aliases presented in the H.323 registration request must be in the list of allowed device aliases. If any alias is not present, none of the aliases will be allowed to register. Additionally, if device authentication is being used, all of the aliases presented in the request must use the same credentials.

• If your endpoint supports SIP and H.323, you should register it to Pexip Infinity over just one protocol, either SIP or H.323, but not both.
• To register an Infinity Connect client, enter either the IP address or FQDN of a local Conferencing Node, or the IP address or FQDN of the reverse proxy, as the registration server address. Infinity Connect clients register over the WebRTC protocol. For more information about how to register an Infinity Connect client, see Registering your device to receive calls.

After the device has registered it must periodically refresh that registration.

Calling registered devices

Whenever Pexip Infinity needs to place an outbound call (such as when adding a participant to a conference, or when making a call via the Pexip Distributed Gateway), it will first look through the set of devices currently registered to any of the Conferencing Nodes on the Pexip Infinity platform. If the alias it is trying to call is currently registered, then Pexip Infinity will place the call to that registered device.

When calling a registered device:

• the Conferencing Node to which the device is registered will place the call to the device (media may flow through other nodes, as per the platform's standard distributed conferencing behavior)
• the outbound call is always placed to the registered device over the same protocol that it used to make the registration
• if multiple devices are registered with the same alias, Pexip Infinity will place a call to each device, i.e. it will fork the call.

Requirement for Call Routing Rules

Note that, in most cases, you must also configure a suitable Call Routing Rule that instructs Pexip Infinity to place the outbound call (either to the registered device or to any other non-registered device or system). A Call Routing Rule is required when:

• making a call to another device or system via the Pexip Distributed Gateway
• using Automatic routing when adding a participant to a conference.

A Call Routing Rule is not required when:

• using Manual routing when adding a participant to a conference.

When configuring rules you must define:

• whether the rule applies only to incoming Pexip Distributed Gateway calls, or only to outgoing calls placed from within a Pexip Infinity conference (where Automatic routing has been selected), or to both incoming gateway calls and outgoing calls from conferences
• the destination aliases to be matched — this needs to match the pattern of the registered device aliases
• whether to route the call to Registered devices only (in which case the call will fail if the device is not currently registered), or to Registered device or external system which will route the call to a matching registered device if it is currently registered, otherwise it will attempt to route the call via an external system.

Avoiding call looping

Call Routing Rules that are intended to route calls to devices registered to Pexip Infinity (e.g. Infinity Connect clients) could, depending upon DNS configuration, result in call looping if the destination device alias is not currently registered.

This can occur if the Call Routing Rule handling those calls has its Call target set to Registered device or external system. In this case, if the alias is not currently registered, Pexip Infinity will attempt to place the call via DNS or a call control system. This could result in the call being routed back to Pexip Infinity which would then match the same Call Routing Rule and result in a loop.

To avoid this, we recommend that you configure your Call Routing Rules that match the pattern of registered device aliases to use a Call target of Registered devices only. This ensures that the call will fail cleanly without looping if the device is not currently registered.

To avoid this, we recommend that you configure a Call target of Registered devices only for your Call Routing Rules that match registered device aliases. This ensures that the call will fail cleanly without looping if the device is not currently registered.

Note that in earlier versions of Pexip Infinity before the availability of the Registered devices only option, we previously recommended configuring a SIP proxy with an address of nowhere.invalid. This workaround will still avoid the call looping issue, but if you have any existing rules that use this method, we recommend modifying them to use a Call target of Registered devices only instead.

Call routing logic

The stage in Pexip Infinity's call routing logic where it checks if a device is registered is highlighted in the following diagram:

Configuring the registrar service

Devices can only register to Pexip Infinity if the registrar service is enabled.

To configure Pexip Infinity's registrar service, go to Service configuration > Registrar. The options are:

Option	Description
Enable registrar	Controls whether devices can register to Pexip Infinity. Devices must register with a permitted alias (configured via Service configuration > Device aliases). The registrar service is enabled by default.
Registration refresh (general)
Registration refresh strategy	Defines which strategy to use when calculating the expiry time of a SIP or H.323 registration: Adaptive: Pexip Infinity automatically adjusts the refresh interval depending on the number of current registrations on the Conferencing Node handling the registration request, in order to spread the load of registration refreshes. As the number of devices registered to a Conferencing Node increases, the refresh interval calculated by Pexip Infinity will also typically increase, although it will always be within the bounds of the configured minimum and maximum refresh intervals. Basic: Pexip Infinity simply uses the configured minimum and maximum settings, along with the requested value, to determine the refresh interval. Default: Adaptive.
Minimum refresh interval (Adaptive strategy)	The minimum interval in seconds before a device's registration must be refreshed, when using the Adaptive strategy. Default: 60 seconds.
Maximum refresh interval (Adaptive strategy)	The maximum interval in seconds before a device's registration must be refreshed, when using the Adaptive strategy. Default: 3600 seconds.
Minimum refresh interval (Basic strategy)	The minimum interval in seconds before a device's registration must be refreshed, when using the Basic strategy. Default: 60 seconds.
Maximum refresh interval (Basic strategy)	The maximum interval in seconds before a device's registration must be refreshed, when using the Basic strategy. Default: 300 seconds.
Registration refresh intervals for SIP endpoints behind NATs
Minimum refresh interval (when behind NAT)	The minimum interval in seconds before a device's registration must be refreshed, for a SIP endpoint behind a NAT. Default: 60 seconds.
Maximum refresh interval (when behind NAT)	The maximum interval in seconds before a device's registration must be refreshed, for a SIP endpoint behind a NAT. The refresh interval for SIP endpoints behind a NAT typically has to be shorter than the interval for other endpoints. This is to help keep the NAT pinhole alive. Default: 90 seconds.

Note that:

• In all circumstances, requests for a value lower than the relevant Minimum refresh delay will result in the registration being rejected.
• The registration refresh strategies apply only to SIP and H.323 endpoints. Infinity Connect clients have a fixed refresh interval of 120 seconds.

Specifying which aliases devices are allowed to register with

Devices can only register to Pexip Infinity with a permitted alias.

To configure the aliases that devices are allowed to register to Pexip Infinity, go to Service configuration > Device aliases. The options are:

Option	Description
Device alias	The alias URI with which the device must register to Pexip Infinity. The alias must be an exact match; regular expressions are not supported.
Service tag	This optional field allows you to assign a unique identifier to this service, which you can then use to track use of the service. For more information, see Tracking usage with a service tag.
Description	An optional description of the device.
Username and Password	The username and password credentials with which to authenticate the device. The credentials are optional and the device is not challenged if no credentials are entered. The username and password are case-sensitive.

Troubleshooting and logging

To see a list of all device aliases that are currently registered to the Pexip Infinity platform, go to Status > Registrations.

Successful registration requests and expired registrations are recorded in the administrator log.

Failed registration requests (due to, for example, an unknown device alias or authorization failure) and refreshed registrations are recorded in the support log only.

If a call fails to be placed to a registered device, check that an appropriate Call Routing Rule has been configured that has suitable destination alias matching strings for the registered alias (and ensure that call looping cannot occur).