SIP T-28P losing registration

[Sepp]

Hardware: T-28P, Firmware 2.70.0.140

Problem: We have 2 identical phones (same type as above, same firmware, same configuration) in 2 different places. One is hooked on a ADSL line, the other on a tv cable account. Same router (identically configured), same VoIP provider, just a different number.

The phone on the cable works fine, but the phone on the ADSL tends to lose registration after not being used for some hours. I exchanged the phones within the arrangement but still the same problem.

Does the phone on the ADSL need a different configuration (see attachment)? Any other idea?

Thanks for your help,
Sepp

[Yealink Support]

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?

[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

[elementpbx]

Change your registration time from 3600 to 240 and test for a day. If it stays registered then most likely the DSL modem / Router is timing you out.

Is it a straight modem or does the DSL have a firewall?

[Sepp]

I will do this when I am in that location next time (it's my holiday house). As to the DSL firewall: I will ask the phone company and let your know.

Thanks for your efforts.