[asterisk-users] Softphone to be installed on the Mobile

[Steve Kennedy]

On Wed, Nov 21, 2007 at 11:35:42AM -0500, Dean Collins wrote:

> There's an application server that sits between asterisk and the gprs network that can switch calls real time between wifi, your office pabx extensions and the gsm network.
> I've forgotten the name of it but I remember it costs $US6,000 for 10 licenses.
> If you want me to find out more I can spend the time to look into it but only after you've said yes to the budget.

There are several methods allowing you to do this, but most are operator
dependent.

UMA (unlicensed mobile access), which is an unfortunate name as in
several countries (including all of EU) all spectrum is licensed (though
some is license excempt - which isn't unlicensed). This uses a home
basestation which connects back to the GSM operator over IP. There's
basically a switch in the GSM core which can flip between the call over
GSM or WiFi. In the UK BT call this Fusion (in conjunction with
Vodafone).

Companies like Truphone run a software shim on the phone. When you make
a call it actually prefixes the outbound call with a Truphone prefix, so
if it's via GSM the call actually goes through them. That way they get
termination revenue from the mobile networks, which hopefully covers [1]
the cost of the actual onward call. If in range of a WiFi network the
phone establishes a connection to an end-point in Truphone's network and
switches the call (and if the WiFi degrades, it switches back to GSM).

Both the above assume that the calls terminate on a system controlled by
the network (or Truphone), so that sessions can be controlled by them.

It would be possible to do this with software in the phone and all calls
terminating on your kit which then passes the call on to the PSTN, so if
WiFi is available it can originate the call from there, but it needs to
switch to GSM/etc if you move out of range - so you need to be in
control of both end-points of the call.



Steve

Note [1] Truphone took T-Mobile to the High Court in the UK as T-Mobile
refused to route their number block. They won and T-Mobile were forced
to route Truphone's numbers. The court also ruled that as they were
providing a VoIP service, they should only get sub-pence termination
rates - which means they don't cover onward call rates (as they
terminate to traditional telcos), so although Truphone won the battle,
they pretty much lost the war.

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