When cable operators offer telephony services over their networks, they do so based upon the PacketCable standards. At least, in the United States. In Europe there is EuroPacketCable. But what is the difference and what were the drivers for it? Find out in this blog post.
The PacketCable industry standard is a set of specifications developed by CableLabs. These specifications define the blueprint for an architecture for offering telephony services in cable networks. Although the telephony service is technically voice over IP (VoIP) based, it gets enhanced quality of service (QoS) treatment to really give the telephony service the same user experience and quality as the landlines it competes with.
In Europe we use EuroPacketCable instead. For the most part EuroPacketCable is based on the same specifications as PacketCable, but there are differences in some areas, mainly related to:
- the use of DOCSIS or EuroDOCSIS;
- the analogue interface towards the phone;
- the configuration files and provisioning;
- the connection to the public switched telephony network (PSTN);
- the digital certificates.
Let’s take a closer look.
Building upon DOCSIS or EuroDOCSIS
Because PacketCable is based on IP, the Internet Protocol, it of course relies on DOCSIS to provide the IP connectivity over cable networks. In Europe, and many other parts of the world, cable networks however use the EuroDOCSIS variant. Therefore EuroPacketCable assumes EuroDOCSIS as the underlying layer. The differences between DOCSIS and EuroDOCSIS are the subject of another blog post.
The analogue interface, also called the POTS (Plain Old Telephone Service) interface, has different properties in different parts of the world. Think about voltages, timings, tones you hear (e.g. the dial tone), caller ID delivery, ringing the phone… For PacketCable the POTS interface must comply with GR-909 while for EuroPacketCable this is ETSI TS 101 909 part 18.
If a cable modem has POTS interfaces, we call it an E-MTA (Embedded Multimedia Terminal Adapter) or E-DVA (Embedded Digital Voice Adapter), depending on whether you’re thinking in terms of (Euro)PacketCable 1.x or (Euro)PacketCable 2.0 terminology.
MIBs and provisioning
The telephony part of an E-MTA or E-DVA is managed through its own set of MIB modules (Managed Information Base). Part of the configuration settings have to do with the POTS interface properties. However it turned out that the PacketCable MIBs were not detailed enough to be able to express all European country variations in them. Therefore an effort was made to make international versions of these MIBs, and it is those versions that EuroPacketCable uses. If you want to look them up, they’re IETF RFC 4682 and RFC 5098 or even draft versions thereof.
An important practical consequence is an incompatibility between PacketCable and EuroPacketCable E-MTA/E-DVA provisioning:
- the configuration files are different due to the different MIB definitions;
- the SNMP messages used in the Secure and Hybrid provisioning flows are different because they use these MIB definitions as well.
Interfacing with the PSTN
There are differences in public switched telephony networks (PSTN) between continents to take into account as well. This impacts for example the Signaling Gateway (differences in SS7) and the Media Gateway (Amercian T1-trunks versus European E1-trunks). Also the intermediate Line Control Signaling architecture is impacted (using the American GR-303 interface versus the European V5.2).
As an aside: you will typically find differences in offered call features between PacketCable and EuroPacketCable networks. However, regardless of specification requirements, the call features will be country and operator dependent.
(Euro)PacketCable defines robust security mechanisms based upon a public key infrastructure (PKI). Such a PKI is all about digital certificates, and they are different for PacketCable and for EuroPacketCable. This difference is mainly due to both standards using different root certificates, allowing for separate certificate hierarchies and separate certificate authorities.
The bottom line
People interested in PacketCable/EuroPacketCable differences are usually especially interested in the E-MTA or E-DVA devices only. Usually the version of DOCSIS they use is quite clear, so for the rest especially look out for:
- which MIBs they use, with consequences for configuration files and provisioning flow;
- which digital certificates they have installed;
- what the POTS characteristics are and if they match your country requirements.
You get this right, and you’re already a long way to having an E-MTA or E-DVA running.