telekom dsl router compatible with o2 internet connection ?

Experience has shown that there are no problems with the internet connection. However, telephony often does not work with vendor-specific devices!

There are no reports about the router with O2DSL so far.

@ administration: bitte zum english forum verschieben

Thanks for the response. So for the telephony so they provide telephone as well or they give sim card or how does it work?

Telephone will work over SIP (VoIP).

Buy a FRITZ!Box 7520 from eBay, not very expensive and will work fine.

If you would like to use SIP as well, I would recommend to try the Speedport W925V you already own first. Experience has shown that Speedport devices from Arcadyan usually also work with o2 IP telephony. I cannot find any experience reports on the specific model 925V. It would be appreciated if you share your experiences here in the forum. 

Thanks everyone. I decided to buy o2 homebox 2 so as to avoid any connection issues.

What you write is not possible. o2 Homeboxes are not sold, but are exclusively rented/leased as a tariff option for o2's DSL tariff. It is generally not possible to purchase the devices. 

The units are bound to the respective connection via the serial number. If you try to obtain a stolen device from another customer, telephony on your connection will not work with it. There is also no support from o2 for devices that are not rented from o2. 
I strongly recommend that you return the illegally obtained device to where it came from. 

Please buy a FRITZ!Box 75x0 the box will work fine with O2.

The rent of a HomeBox will charge you with 49,99€ onetime fee + 4,99 post and package.

And 3,99€ / Monthly fee.

The FRITZ!Box 7530AX is about 150€ and a excellent router.

150€ - 49,99 - 4,99 = 95,02 / 3,99 = 23 Month ROI!

So you will get a much better router for the same price as the low cost homebox with worth WLAN and many other little problems!