Remote friends

Remote friends connect a vPBX client with an external SIP entity.

Types of remote friends

There are 2 main types of SIP PBX that can be integrate with IvozProvider:

  • Direct connection PBX (Connectivity mode: direct): IvozProvider must be able to talk SIP directly with this kind of friends by just redirecting the traffic to the proper port of the public IP address of the PBX.
  • PBX behind NAT (Connectivity mode: register): Not directly accessible. This kind of PBX must register at IvozProvider (just like all the Terminals do).

What do remote friends allow?

This section allows not just communication between users at boths ends of the SIP trunk, but also:

  • Users “from the other side” can call to the public network just like native Ivozprovider Users.
  • Public network calls can be routed to the other SIP trunk end.

What kind of calls can be routed through a remote friend?

IvozProvider must know what calls must be routed to the different defined remote friends. For that, client administrator will configure regular expressions that describe the numbers that can be reached through the friend.

Note

Internal extensions have priority over any expression defined in the friends.

Important

Avoid PCRE regular expressions in friend configuration: use [0-9] instead of \d.

Configuration of remote friends

The Friend configuration is a merge between a User and a Terminal

These are the configurable settings of friends:

Name
Name of the friend, like in Terminals. This will also be used in SIP messages (sent From User).
Description
Optional. Extra information for this friend.
Priority
Used to solve conflicts while routing calls through friends. If a call destination matches more than one friend regular expression the call will be routed through the friend with less priority value.
Password
When the friend send requests, IvozProvider will authenticate it using this password. Using password IS A MUST in “Register” mode. In “Direct” mode, leaving it blank disables SIP authentication and enables IP source check.
Connectivity mode
Choose between “Direct” and “Register” for a remote friend.
Call ACL
Similar to internal users, friends can place internal client calls without restriction (including Extension or other Friends). When calling to external numbers, this ACL will be checked if set.
Fallback Outgoing DDI
External calls from this friend will be presented with this DDI, unless the source presented by friend is a DDI that exists in DDIs section.
Country and Area code
Used for number transformation from and to this friend.
Allowed codecs
Like a terminal, friends will talk the selected codec.
From user
Request from IvozProvider to this friend will include this user in the From header.
From domain
Request from IvozProvider to this friend will include this domain in the From header.
DDI In
If set to ‘Yes’, set destination (R-URI and To) to called DDI/number when calling to this endpoint. If set ‘No’, username used in Contact header of registration will be used, as specified in SIP RFC (friend name will be used for endpoints with direct connectivity). Defaults to ‘Yes’.
Enable T.38 passthrough
If set to ‘yes’, this SIP endpoint must be a T.38 capable fax sender/receiver. IvozProvider will act as a T.38 gateway, bridging fax-calls of a T.38 capable carrier and a T.38 capable device.
Always apply transformations
Both numbers listed in Extensions section and numbers matching any friend regexp will be considered as internal and won’t traverse numeric transformation rules. Enable this setting to force Numeric Transformation rules even on these numbers.
RTP Encryption
If set to ‘yes’, call won’t be established unless it’s possible to encryption its audio. If set to ‘no’, audio won’t be encrypted.
Multi Contact
Same SIP credentials can be configured in multiple SIP devices. In that case, all devices ring simultaneously when receiving a call. Setting this toggle to ‘No’ limits this behaviour so that only latest registered SIP device rings.

Note

Calls to friends are considered internal. That means that ACLs won’t be checked when calling a friend, no matter if the origin of the call is a user or another friend.

Tip

Friend can be contacted due to calls to several extensions/DDIs. DDI In setting allows remote SIP endpoint to know which number caused each call, setting that number as destination (R-URI and To headers). This way, friend can handle calls differently.

Asterisk as a remote friend

At the other end of a friend can be any kind of SIP entity. This section takes as example an Asterisk PBX system using SIP channel driver that wants to connect to IvozProvider.

register

If the system can not be directly access, Asterisk will have to register in the platform (like a terminal will do).

Configuration will be something like this:

register => friendName:friendPassword@ivozprovider-client.sip-domain.com

peer

[friendName]
type=peer
host=ivozprovider-client.sip-domain.com
context=XXXXXX
disallow=all
allow=alaw
defaultuser=friendName
secret=friendPassword
fromuser=friendName
fromdomain=ivozprovider-brand.sip-domain.com
insecure=port,invite
sendrpid=pai
directmedia=no

Warning

Friends, like terminals, MUST NOT challenge IvozProvider. That’s why the insecure setting is used here.

Note

As From username is used to identify the friend, P-Asserted-Identity (or P-Preferred-Identity or Remote-Party-Id) must be used to specify caller number. Prevalence among these source headers is: PAI > PPI > RPID.

Summary of remote friends

The key point is understanding that a remote friend has a direct relation with the extension-user-terminal trio:

  • Can place calls to all internal extensions and other friends.
  • Can place external calls that its ACL allows
  • Display their configured outgoing DDI when calling to external entities
  • Never challenge IvozProvider requests (don’t request authentication on received requests)
  • Answers IvozProvider authentication challenges (All request from them to IvozProvider must be authenticated for security reasons)
  • Only connects with Users SIP Proxy, like terminals. In fact, SIP traffic from friends are identical to any other user terminal traffic in format.