UPDATE: Recent Fritz!Box OS allow to choose between Internet or Voice VLAN when configuring VoIP accounts. See AVM provides workaround to use 3rd party ITSPs. The statements below are obsolete.
Yes it does, unfortunately.
So why exactly? The short answer is, because the VoIP part of the Fritz!Box is moved to an isolated virtual LAN (VLAN) with no Internet access, so the Fritz!Box VoIP part cannot reach any alternative VoIP services as these are somewhere on the Internet.
But why is this necessary? The LuxFibre product is designed to provide all services over IP. This includes any telephone services (analogue, ISDN) which were previously delivered directly via copper. Telephony over IP cannot deliver the same quality and availability out of the box as traditional telephony services. The regulation however requires all operators to provide the same level of quality and availability on telephony over IP services, hence the requirement to differentiate services on the LuxFibre product. EPT selected the way of 1 VLAN per service:
- Internet access VLAN 35
- Voice VLAN 39
- TV VLAN xy
Using different VLANs makes it quite easy to prioritize one VLAN over another and to configure guaranteed bandwidth. By these means EPT can meet the regulatory requirements for quality and availability of their Telephony service. Additionally as all the services are produced within the EPT network, none of the VLANs need to provide Internet access (except for the Internet access VLAN itself). So the Voice and TV VLANs do not provide any Internet access at all. This also allows EPT to completely isolate their VoIP and IPTV systems from the Internet, hence protecting the systems themselves but also the users from being attacked. The Fritz!Box supports this kind of setup by allowing the usage of different VLANs for the different services provided via the Fritz!Box. The sad thing about it is that you cannot select the VLAN per VoIP service but only for all VoIP accounts.
The consequences are that you can either use your EPT VoIP service or reconfigure your Fritz!Box to support all other VoIP services beside EPT, but you can never run both from the same Fritz!Box.
A common work-around is to use your old Fritz!Box (in case you had one prior to ordering LuxFibre) and connect it as a client behind your LuxFibre Fritz!Box (aka P&T HomeServer). The 2nd Fritz!Box will use the regular Internet access just like any other device you connect to the Fritz!Box (e.g. PlaySation, Wii, Laptop, etc). You could even daisy-chain your EPT VoIP Service via the S0 (ISDN) interface on the P&T HomeServer to the second Fritz!Box, giving you access to all your telephony services from any phone connected to the 2nd Fritz!Box.
Another work-around is the usage of VoIP telephones (e.g. Gigaset IP DECT), as before you may even daisy-chain your EPT VoIP service via the FON1 (anlaog) in case the chosen telephony support an analog line.