How to distinguish external bluetooth devices

Hi all,
I am writing a connection manager component for my application.
I need to create connections and all other parameters via code, then I
use OpennetCF connection Manager to connect to the destination I need.
In more detail, I do the following steps:

- Create Ras Connection, using the modem I'll define next step, using
the ras API.

- Create a new HKLM\ExtModems\New_Modem voice with the infos about the
extra AT commands and the port to use. For example:
[HKEY_LOCAL_MACHINE\ExtModems\GPRS Bluetooth]
"Port"="BTC1:"
"DeviceType"=dword:00000001
"FriendlyName"="GPRS Bluetooth"
"init"="AT+CGDCONT=1,\"IP\",\"web.omnitel.it\"

- Create a new HKLM\SOFTWARE\Microsoft\ConnMgr\Destinations\New_destination
wih the info about the destination I will choose using connection
Manager's connect method. For example:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ConnMgr\Destinations\GPRS]
"DestId"="{EE19A8C7-1A5B-40D7-85A9-B7AAD441D828}"

- Bind the info about the RAS connection I created, adding the correct
values in the registry at
HKLM\SOFTWARE\Microsoft\ConnMgr\Providers\{7C4B7A38-5FF7-4bc1-80F6-5DA7870BB1AA}\Connections\Ras_Entry
for example:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ConnMgr\Providers\{7C4B7A38-5FF7-4bc1-80F6-5DA7870BB1AA}\Connections\GPRSNokia]
"RequirePw"=dword:00000001
"Enabled"=dword:00000001
"EntryType"=dword:00000000
"DestId"="{EE19A8C7-1A5B-40D7-85A9-B7AAD441D828}"


Doing so, when I connect to the GPRS destination, The GPRSNokia Ras
connection should be dialled, using the modem I specified under the
extmodems key.
My problem is that the extmodem is the bluetooth port, which connects
to a Nokia phone. But I have also a UMTS phone associated with the
PDA, and the call is send to that phone instead of the nokia one. so
the question is:

How can I distinguish between all the dispositives associated to my
PDA via bluetooth, to be able to talk with the one I need?

My hardware is: Hp Ipaq 5550, pocket Pc 2003; Nokia i6310; motorola
a835
Hope someone can help me!!
Thanks
Francesco