[asterisk-users] Wifi GSM handover

[Frank Bulk]

The approach to Wi-Fi to GSM handover differs depending if its handled by
the cellular carrier or enterprise PBX.  

If it's handled by the cellular carrier (as in the case of UMA) there's the
advantage of not tying up additional trunk lines for incoming calls, but
unless the rest of the enterprise is with the same carrier, there's no
short-digit dialing to co-workers, mobile or at their desk.

If it's handled by the PBX, then depending on what client is built on the
smartphone, the end-user can access the key PBX features.   Call control
becomes a little trick.  The general approach is that all calls that come
into the enterprise PBX.  If the end-user's phone is in Wi-Fi mode, a new
VoIP-based call leg is established, either over the LAN, WAN, or Internet.
If the end-user's phone is in cellular mode, the convergence appliance must
create a new PSTN-based call leg.  In either case, the software on the
(smart)phone communicates either in-band or out-of-band (cellular data,
usually) with the convergence appliance so that the appliance knows the
connectivity state of the (smart)phone.  When outbound calls are made,
usually the (smart)phone client calls the PBX, and then patches it through.
This provides a consistent call flow experience, including the ability for
the organization to tracks calls (CDRs), the ability for the end-user to
transfer calls, conference people in, etc.

Both of the vendors I mentioned should have whitepapers/documentation on how
their products work.

Frank


-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Patrick
Sent: Saturday, October 10, 2009 3:17 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [asterisk-users] Wifi GSM handover

Thank to Frank and Steve for your answers

My understanding is that you need to place on operator premise an
equipment that checks first the availability of the user on VoIP. If
not registered, it's routing the call through the cellular network.
Is it correct ?

But during the handover (wifi to GSM), how does it works ? Is it the
operator that initiates a call on the GSM network. If so, I guess the
mobile device need to have some logic to seamlessly switch between the
2 channels, isn't it ?
If it's the mobile device that initiates the call to the GSM network,
it will also require some logic to do that.

So my question is, is the handover something standard in every mobile
device supporting GSM and VoIP or do you require an extra piece of
software to do the trick ?
Is this principal applies to every "transport technology", I mean VoIP
through WIfi or VoIP over 3G ?

Thanks in advance
Patrick


On Sat, Oct 10, 2009 at 06:57, Frank Bulk <frnkblk at iname.com> wrote:
> There are two commercial vendors that come to mind, namely DiVitas and
> Agito.
>
> Frank
>
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Patrick
> Sent: Friday, October 09, 2009 8:15 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [asterisk-users] Wifi GSM handover
>
> Hello guys,
>
> I'm wondering what is required and involved in order to provide a
> wifi/GSM handover to customers.
> After googling I haven't found any product/vendor. Do you have an idea ?
>
> Thanks in advance
> Patrick
>
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