SIP hardware questions

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Hello,

I was occupied now already somewhat longer with Asterisk. Mitlerweile has I also one under Debian to to run. Zurzeit hangs dadran Siemens a Office 600 SIP mode. We want to replace the whole telephone system with us in the company with it nearly. Before we however with us into the active test phase go have I still a few questions. In addition Asterisk with a Bri map is to be attached over a ISDN building group directly to a Hicom 150 pro.
Which SIP or IP of telephones gathers best with Asterisk?
Who of you a Siemens knows white which one if one the direct-inward dialings on the abbreviated dialing gropes programs these e.g. flash someone calls if there, is possible this also with SIP? Furthermore I would gladly know whether Asterisk the ISDN map and/or channels (e.g. a Eicon Diva Bri) occupies dynamically.
I hope to help it there me can.

A beautiful evening still

friendly greets
Franc