Strange problem with NetTalk apps

[tcp]

I've a very strange problem with my freephoneline (configured on a Cisco PAP2T) and the NetTalk apps. I'm using the free NetTalk apps to do some test. Everytime I use the NetTalk apps, the PAP2T green light will disappear and all the calls will start routing to the NetTalk apps. I've an Android and an Ipod Touch with NetTalk installed and it occurs on both devices. When I logged in to the freephoneline, it still indicates:

SIP Status: connected
SIP User Agent: Linksys/PAP2T-5.1.6(LS)

But calls are already going to the NetTalk Apps.

The freephoneline is configured on a Cisco PAP2T using the settings from this link:

http://voipfan.net/ATAs/PAP2_freephoneline.php

The NetTalk apps does not have any configuration, just the login username and password. After loggin in, you can make free calls.

What could be the explanation?

[dibsmft]

Since you have had no reply (I don't have any Apple devices)....
Freephoneline only allows you to use it on one device at a time which will normally be the last one that you connected and hence your observations if you also have the Apple logged into Fongo.

[cu2o2o2]

Let me guess, as there is not enough information given:

Your Nettalk app is using the same ip that is being used by your PAP2T.