VR2600v - Problems with Fax over VOIP

VR2600v - Problems with Fax over VOIP
VR2600v - Problems with Fax over VOIP
2017-05-06 00:26:56
Model :

Hardware Version :

Firmware Version :


Model : VR2600v
Hardware Version : v1
Firmware Version : 1.3.0 0.8.0 v004f.0 Build 160622 Rel.36010n
ISP : Congstar (Germany, Telekom-VDSL2)


I'm using the VR2600v together with a Congstar-VDSL2-Connection (basically Telekom-VDSL2). After some smaller problems at the very start, the router is running pretty smooth (with the exception of only under-average WLAN-coverage and power). There's only one problem, that I wasn't able to fix, yet. I´m using a HP OfficeJet Pro 8730 multifunction-fax-printer. Before I moved, my last internet provider was Vodafone with cable internet. Sending a fax was not a problem at all, everything went smooth out of the box
(connected to the standard cable modem). With the Congstar-VDSL2 things look quite different. I'm not able to send any faxes, dialing works but shortly after sending is initiated, my OfficeJet cancels sending and reports some unspecific transmission error / line error. I´ve tried quite a lot of settings, but nothing really help. T.38 is not supported by Congstar.

I was wondering if anyone else is experiencing similar problems sending faxes over VOIP or if there's some beta-firmware, which may fix such problems. I can also post my current settings for VOIP if necessary.