Howto:Mobile Extension

From innovaphone-wiki

Jump to: navigation, search

Some customers like to have their employees cellular phones integrated as pseudo extensions into the PBX.

While there are sophisticated solutions (a.k.a “mobile extensions”) available on the market, basic requirements can be fulfilled using standard innovaphone PBX features.

Here is how.


Applies To

This information applies to

  • innovaphone Pbx

Build 05-5903 and later (note that this is obsolete from V8, use mobility and/or fork instead)

More Information

Problem Details

While PBX extensions enjoy a number of supported features, employees with cellular phones in addition to their normal extension often want to integrate their cell phone like just normal extensions.

Basic requirements include

· Cellular phones can be called via short dial (for example using a prefix like 67, if the users extension is 72, then her cellular can be called via 6772)

· The cellular phone’s busy status is seen by the CTI application

· The cellular number is hidden to external callers

· Cellular phones can place calls through the main PBX (2 stage dialing), allowing outgoing and incoming calls to be tracked be the PBX’s billing and monitoring system.

Also, cost reductions may be achieved by using only the PBX’s mobile service number for outgoing calls.

System Requirements

The basic solution described here requires

· To define each cellular as a separate user in the PBX, thus consuming a PBX registration license

· A waiting queue for the 2 stage dialing function.

· A web server (or via the Compact Flash Slot)and an appropriate announcement for the waiting queue.

Access to this will require a GWxx entry.

However, this does not need to be dedicated, so you can share asingle access for all applications using web announcements.

· 2 GWxx entries in the gateway implementing the trunk access.


Except for the web server (or via the Compact Flash Slot) for the announcement, no special soft- or firmware needs to be installed


Numbering plan

Although there is not strict requirement to allocate a certain numbering space for cellular phones, users usually find it more easy to understand and memorize if all cell related functions are in a common numbering space.

In this example, we have allocated the numbering space starting with “67” for the cellular system.

Also, in our example, the numbering plan for “normal” extensions has 2 digits. As a convention, for cellular phone of a user with extension “xx”, we use extension “67xx”.


Waiting queue

The waiting queue has extension 670.

Long name and name are set to “cell-dial”.

The queue will accept calls after a short alerting period (we have chosen 1 second).

Only the 1st announcement needs to be configured, the exact settings here depend on your announcement source configuration.

If you already have a path to your web server through a gateway’s HTTP interface, use this.

If not, you will need to configure such path (see below).

It is important to enable the DTMF 2-stage dialing in the 3rd page.

For this, you simply need to map each digit to itself.


HTTP Interface

If you already have a path to your web server configured, use this.

If not, you will need to configure one as follows.

Create a standard user entry with name “announce”.


Create a GWxx entry that registers at the PBX user “announce”.


Create a route from the PBX user GWxx to the HTTP interface.


Registration of cellular phones to the PBX

Create a GWxx entry to register all cellular phones with the PBX.

The key point to understand here is that all phones are registered using a single PBX entry.

That is, a single registration from the GWxx configured will result in many registrations on the PBX.

Use a registration as client mode.

Add an alias to this GWxx for each cellular phone, use its extension (“67xx”) as E164 and an appropriate name as H.323 name.

In the PBX, add each cellular phone as standard user object.

Use an appropriate long name, use the H.323 name you have used as an alias above as name and use the E164 number you have used above as number.

This user object is an ordinary user object and behaves like that.

You may do whatever you feel to it, e.g. add it to groups etc.


Defining Routes from and to the cellular Phones

As your cellular phones are now registered with the PBX, calls to them will be routed the gateway level.

The purpose here is to map the extension numbers to “real” cellular numbers and to route the call back then to the PBX.

While the mapping could be achieved using a PBX MAP object too, this would not allow the cellular to be seen by the SOAP system and thus your CTI application.

To route the calls back to the PBX, you will need a routing entry into the PBX.

If you already have an “EXTERN” registration, you can use this. If not, you will need to configure a separate GWxx for this as follows.

In the PBX, create a user object with name like the H.323 name you used for the GWxx.

Be sure to set the “gateway” option.

In our scenario, this user does not need a number as it is never used for outgoing calls.

Create a GWxx which registers with the PBX as gateway.


To configure calls to cellular phones, add a route from the gateway that registers your cellular phones as defined above (GW4 in our example) to the routing entry of the PBX.

In this route, map each phones short-dial extension (as defined above in the PBX) to the “real” phone-number.

Make sure you define the appropriate trunk access code if required.


To configure calls from cellular phones through the PBX, create a route from your trunk line to the GWxx entry that registers your cell phones with the PBX.

Add a map that routes all calls unchanged (that is, no called number in and no called number out).

Make sure both the “final route” and “verify cgpn” flags are set.

Then add CGPN maps to this route, one for each cellular phone.

In these maps, map the cellular phones real number (as it is seen in the gateways routing, usually without trunk access code) to the cell phones pseudo extension.

Then, add a last map which routes calls to the 2-stage dialing waiting queue to TEST.

This map is crucial as it prevents external callers to use your PBX for outgoing calls on you cost.


Known Problems

As with all mobile solutions, cell phone users will effectively loose their local phone book (as they must not dial out directly any more but go through 2-stage dialing).

One solution to that is a cellular that supports “calling card operation”.

In this mode, the cellular will for each call first call the calling card number, then the desired target using DTMF.

If your cells do support this, configure the number of your 2-stage dialing waiting queue as calling card number.

Professional mobile extension solutions will address this problem by providing a dialable phone book in the 2-stage dialing phase.

Also, such solutions will support a lot more features on the cellular phone, like putting calls on hold, transferring calls or setting up 3PTY conferences.

When calling out to a cell phone, it is desriable to send the calling line id of the original caller to the cell.

The innovaphone PBX will do this in fact, however, under normal circumstances this calling line id is rejected by the carrier and replaced by the trunk lines base number.

This is because the number sent is not associated to the trunk line (that is, to the carrier it looks like spoofing invalid calling party numbers).

The only solution here is to enable "clip no screening" on the trunk line (there is a separate wiki Howto:How does "CLIP no screening" work? article about this topic).

There may be an issue when external users are calling mobile extension and the "if an incomplete number is dialed" diversion in the trunk object is used.

The timeout to detect incomplete numbers is 4 seconds and the cellular network (where the call to the mobile extensions actually is routed to) may be too slow to respond within this time.

To work around, either do not use this diversion type or upgrade your pbx to build 05-5917 or later.

For professional 3rd party mobile integration soloution please refer to the related articels

Related Articles

Howto:Quescom Mobility Services Pack - SIP Testreport

Howto:SPEECH DESIGN Teleserver Mobile Pro, iCE information

Personal tools