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Hello.
Since 2 month I am using the TP Link VR 2600 v Router with German Telekom as ISP.

Internet and phone is working but ...

I need help with the following problem:

--> If I want to make phone calls, it occurs, that these calls are not completed.
I dial the number,
I can hear the sound of dialing
... than - after a certain time - the line is mute and I hear the "occupied" signal.

I called my ISP (Telekom) and we figured out, that this happens, if the number I want to call is located by the German Vodafone.
If I call the same phone number by using a "call by call" provider, the call is completed correctly.

Can anybody please give me a hint or the solution ?

Thanks and kind regards.