SIP T-28P losing registration

[Sepp]

(06-06-2013 02:35 PM)Yealink Support Wrote:  Hi Sepp,
Sorry i don't know about the configuration of ADSL line, but Yealink phone should register a VOIP account, and just connect to internet is OK.
Do you mean even you exchange these two phones, the phone which can't register is still can't register on the cable?
Did you exchange the extension?

Hi,
The fact is that the phone which loses registration after some time is always the phone on the ADSL internet line, even if I exchange the phones (or the router or anything else). I assume that the problem is rooted somewhere in the interface between the phone and the ADSL internet access. The phone company that provides the ADSL line has checked it and says that the signal is okay (however they would probably say this anyway...). And once again: If I take this phone away from the ADSL internet line and hook it to the cable tv internet line, then it works forever even if it is not used for a few days.

Funny, isn't it?

Sepp