Copyright 2010-2015 Obihai Technology, Inc.
132
Voice Gateways and Trunk Groups
Voice Gateway
A gateway in this context is another OBi device that lets incoming OBiTALK callers to call further on one or more of its
trunks (such as SP1, SP2, or BT). The caller can call the gateway first with a normal OBiTALK call, get the AA and then
dial the target number. For authentication the AA may ask the user to enter a PIN before establishing the second call.
This way of dialing is known as 2-stage dialing.
On the other hand, a gateway can be configured on the originating OBi device such that the caller can dial the target
number directly without going through the AA. We refer to this method of dialing as direct dialing or 1-stage dialing.
Since it is not possible to enter a PIN in the case of direct dialing, a userid/password pair can be configured for the
gateway also so that the device can authenticate with the gateway automatically using the HTTP digest method. The
HTTP digest authentication is optional. You do not need to provide a user/password if the gateway does not require
authentication for direct dialing.
The OBi allows the user to specify up to 8 gateways. Each gateway is addressed using its factory-assigned OBi Number.
A gateway is conceptually a trunk with its own DigitMap. You can refer to a gateway and its associated DigitMap with
the short trunk name VG
n
and (Mvg
n
) respectively, for
n
= 1, 2, 3, …, 8. VG
n
and (Mvg
n
) can be used in call routing rules
and digit maps just like other real trunks.
As an example, you can add the rule
{(1xxx xxx xxxx):vg2}
in
Phone Settings
::
OutboundCallRoute
to let
the device dial out using VGs when the caller dials any 11-digit number starting with 1. On the gateway side, you can
add the corresponding rule
{>(1 xxx xxx xxxx):sp1}
in the
OBiTALK Service
::
InboundCallRoute
to make
the call on its SP1 trunk. You can change the last rule to
{(290 333 100|200 444 101)>(1 xxx xxx
xxxx):sp1}
if you want to limit the gateway to allow just the two stated caller numbers to make such calls.
A gateway may also be configured with a SIP URL as the access number to be accessed by the device over one of the SP
trunks. For example, one can set the gateway access number as
SP1(some-sip-server.mydomain.com)
, or
SP2(192.168.15.111:5062)
, etc. Note that when using a SP trunk to access a (SIP) gateway, the device will:
-
Not use the outbound proxy, ICE, or STUN regardless the settings on the SP trunk.
-
Use only the device’s local address as the SIP Contact, and ignore any natted address discovered by the device.
-
Use the gateway’s SIP URL to form the FROM header of the outbound INVITE.
-
Use the gateway’s
AuthUserID
and
AuthPassword
for authentication.
-
Apply the symmetric RTP concept.
Trunk Groups
As the name implies, a trunk group is a group of trunks. If a call is routed to a trunk group, OBi picks one of the available
trunks from the group to make the call. Availability of trunk is based on:
-
Whether the trunk’s digit map allows the number to call, AND
-
Whether the trunk has capacity to make one more call
Up to 4 trunk groups can be configured on an OBi device. Each trunk group is conceptually another trunk with its own
DigitMap. A trunk group and its associated DigitMap are referenced using the short name TG
n
and (Mtg
n
) respectively,
where
n
= 1, 2, 3, 4. They can be referenced in other digit maps and call routing rules so that calls may be routed to a
particular trunk group.
Only trunks can be added to a trunk group. These include: PP, SP1 – SP6, BT, VG1, VG2, …, VG8, TG1, TG2, … TG4. Note
that a TG may include another TG (that is, TG can be recursive). However, you must make sure this does not result in
infinite recursion.
