web.de + several sip on different numbers

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Hello together,

I configured my web.de account in asterisk so far that I can be called on arbitrary softphones.
Now I would be gladly on different phones on different numbers attainable, however with only one account.

Speak sip1 => 01212xxxyyyyyy1
sip2 => 01212xxxyyyyyy2
sip3 => 01212xxxyyyyyy3
sip4 => 01212xxxyyyyyy4

thus not for each number an account with web.de

Actually would have nevertheless possible to be if I mean normally isdn number calls rings the telephone (ok, logically) if I behind it however any number select which number and their length is thereby fllig all the same rings the telephone also.

but in asterisk I have this not gotten yet.

Is my project at all possible?
If how?

Thank you already times for your answers.