TELECOM ACCESS STANDARDS NEWSLETTER NO. 154 March/April 2005 CONTENTS 1. VOICE OVER INTERNET VERSUS VOICE OVER IP 2. PTC 220 DEVELOPMENTS 3. INTELLECTUAL PROPERTY ISSUES 4. CUSTOMER PREMISES WIRING FOR NEW GENERATION SERVICES 5. NZ RELAY SERVICE: TTY – 027 HANDSET COMPATIBILITY 6. CELLPHONE “JAMMERS” RETURN TO MAIN INDEX 1. VOICE OVER INTERNET VERSUS VOICE OVER IP There have been several enquiries in recent times over Telecom’s stance towards “voice over internet” as distinct from “Voice over IP”. While the performance standards for the latter have been dealt with in several of these Newsletters and in our draft specification, PTC 220, we have published very little about the former. Many people regard the two terms as synonymous, so it is worth defining what we mean by these terms in our Newsletters and specifications. By “voice over internet”, we are referring to services accessed by users via the public internet, which is essentially a “best efforts” service, with no prioritisation for voice calls. These are simply regarded as “data packets” like any other so may often be subject to delays and packet loss, which result in each call being of variable and sometimes unacceptable commercial quality in one or both directions of transmission. While such services as “Skype”, “Vonage”, etc, may be accessed over Telecom’s ADSL lines, they are NOT Telecom services. Where a customer chooses to use the internet for voice calls via these other providers, any charges those providers levy and the service standards they achieve are none of Telecom’s business. In line with this approach, headsets and sound cards used to make voice calls over the internet are not subject to Telepermit. Nevertheless, it is recommended that they do meet the same transmission standards as “commercial VoIP” wherever practicable. As stated in previous Newsletters, setting the right Loudness Ratings costs no more than setting the wrong ones, so why not get it right? Where “Voice over IP” and PTC 220 requirements are concerned, we are referring to services charged for by Telecom and provided via Telecom’s network. When a customer chooses to use Telecom’s national or international call services and pay commercial rates for those services, it is only reasonable that Telecom sets standards seeking to ensure that end-to-end performance is of commercial quality. As with voice over internet, Telecom has no direct interest where users are making calls wholly within a private network. Whether the call is packet-switched or circuit switched, or voice compression is used, is immaterial. Nevertheless, where a private network is connected to the PSTN we do expect PSTN standards to be maintained for calls into or delivered from the PSTN. For example, private networks are often used for toll by-pass such that a call is carried over IP within the private network and passes to the Telecom PSTN at a remote location. The party originating the call generally knows that the call path is via the private network and can take steps to go directly to the local PSTN should such calls prove unacceptable due to voice compression, delay or packet loss. Nevertheless, it is expected that all such private networks connected to and using Telecom’s PSTN will meet the performance standards recommended by the ITU-T and minimise both delay and packet loss. Network design is outside the scope of PTC testing and PTC 220 compliance only ensures that a correctly designed private network should be able to achieve the required standards when using equipment that has gained Telepermit. 2. PTC 220 DEVELOPMENTS IP GATEWAYS We have received several Telepermit applications for IP Gateway devices which are intended to be used singly or in pairs and not directly connected to the Telecom network. Typically, each Gateway connects to an existing PBX, allowing it to support IP telephones and/or provide for what are essentially IP tie lines between two or more PBX locations. Voice compression may or may not be used to improve the traffic capacity of the inter-PBX links. As recommended in PTC 220, the ideal situation is that all telephony CPE meets the internationally accepted optimum Loudness ratings of SLR = 8 and RLR = 2 at the private network transmission zero reference point, with its levels aligned with those of the public network. If this is achieved, any Gateway devices would incorporate neither gain nor loss. However, problems can arise if the various types of IP telephone having a range of Loudness Ratings are connected “behind” such gateways. One way of dealing with these gateway devices is a standard Loudness Rating test from an analogue PSTN interface to a Telepermitted proprietary telephone connected to the PBX – first measuring levels in each direction of transmission directly via the PBX, then again with the call path switched via the gateway devices connected “back-to-back” to simulate an IP network between two connected PBX locations.  This would confirm that there is no loss or gain difference between the two optional paths.  TIE LINE APPLICATIONS Testing between analogue PSTN ports, first “with”, and then ”without” gateway devices, gives an equivalent pair of tests for tie-line transmission level purposes. Strictly, this comparative test only covers zero loss connection of the gateway devices in back to back mode and may not detect any gains or losses in individual components that are self-compensating.  However, it does allow confirmation that the levels delivered into the PSTN are within the specified limits.   It must not be forgotten that there are other aspects of PTC 220 compliance testing which relate to operational aspects. Similarly, internal PBX functions/features could be affected by the inclusion of the gateway devices and IP network.   For example, such matters as end-to-end DTMF transmission from a telephone to the public network when the gateways and the LAN are involved in the overall path (especially where low bit rate encoding is used); and echo cancellation arrangements where an analogue telephone has been connected at the distant PBX and the round trip delay from PSTN interface to PSTN interface is excessive.   The immediate need is to verify that use of gateway devices does not upset the parent PBX’s transmission plan or basic operations, especially where the gateways are supplied by a third party and not necessarily supported by the PABX provider.   Given that these gateway devices may not directly connect to either analogue or digital telephone sets, nor do they necessarily connect directly to the Telecom network, testing them under the exact wording of the FXS, FXO or FXD requirements set out in PTC 220 is not always directly applicable. Nevertheless, the principles set out in PTC 220 do apply and our need is assurance that the inclusion of a pair of gateway devices will not degrade the performance of the parent PBX to an unacceptable level.  We will be amending PTC 220 to make this point more clear. “OTHER TYPES” OF IP TELEPHONES Telepermitting these Gateway devices under the same conditions as PABX system dependent telephones will be valid only as long as there is no inference that “any” IP telephone may be used with them on calls to or from the public network.  This will be a condition of the Telepermits that are granted.   In the circumstances, each type of IP phone will later need to be tested for compliance with PTC 220 via its proprietary interface and PBX and the IP phone Telepermit will be specific to that combination. ANALOGUE TELEPHONE ADAPTERS Any IP transmission is not necessarily limited to IP telephones. Analogue telephone adapters (ATA’s) are commonly used to connect standard PTC 200-compliant and system proprietary analogue telephones to an IP system. The same testing principles apply as for Gateway devices in that tests of each device can be carried out with the telephones concerned directly connected to the PBX and the same tests can be repeated with the IP components and ATA included.   WIRELESS IP TELEPHONES Another stream of development covers IP Phones and WiFi access points customised for use with a range of different PABX systems. These will also be dealt with as system-integral telephones, testing from the acoustic interfaces of the telephone to the public network zero reference point and confirming that DTMF and other basic signalling operations are satisfactory. BLOCK DIAGRAMS OF TEST ARRANGEMENTS Test labs are asked to ensure that clearly drawn block diagrams are supplied with test results to show exactly what “path” components and terminal devices have been connected for each test. There can be a host of potential connection arrangements, especially with some of the larger and more complex systems, so it is important that all concerned clearly understand what has been tested. TRANSMISSION SETTINGS Another particularly confusing aspect of testing is the actual system settings that have been used during the tests. We have in the past accepted “fully compliant” test results only to find, on enquiry, that no one can specify what transmission settings had been used. It makes things difficult for an installer if the equipment supplier does not clearly specify the transmission settings to be used for both the tests and the actual system set-up for end customers. ACTUAL MEASUREMENT RESULTS Finally, test labs are asked to provide actual measured results, not just “Complies” and that they ensure all the necessary tests are actually carried out. We will often get test reports with the result “noted” instead of an actual test result, implying that no actual test was carried out.   3. INTELLECTUAL PROPERTY ISSUES Telecom is not usually informed of the attitudes of the “parent PABX” manufacturers towards the use of other party’s Gateway devices in their PBX networks.  While some Gateways may be “sponsored” by the PBX supplier as a means of extending their systems to IP operation, others could well be direct “competitors” to those PBX suppliers’ own products and make unauthorised use of the PBX supplier’s proprietary information to achieve full compatibility with the parent PBX.  Any grant of a Telepermit for such a gateway must be regarded simply as Telecom’s agreement to the connection of that equipment and not as any indication that the Telepermit over-rides any objections to the use of those Gateways by the PABX suppliers, other Intellectual Property owners, or their New Zealand agents.   4. CUSTOMER PREMISES WIRING FOR NEW GENERATION SERVICES Home wiring practices have been covered in previous Newsletters and we still recommend the installation of extensive star-wired Cat 5 cable and RJ45 jackpoints in new homes or during major renovations despite the growing availability and reducing cost of WiFi in its various forms. Home installations can vary from today’s very simple loop-wired 2-wire jackpoints through to quite complex installations covering telecommunications, entertainment services and building services monitoring/control. ISO/IEC have recently published a new standard ISO/IEC 15018 “Information technology – Generic cabling for homes” (available from Standards New Zealand). This is expected to soon replace the present SOHO standard, AS/NZS 3086. Telecom is currently working on a series of recommendations for home wiring, including suitable means of phasing in RJ 45 jackpoints for home applications, and more will be published on these issues in these Newsletters. The aim is to align with ISO/IEC 15018, but present recommendations and options in a simpler and briefer form. The basic message is that new homes are expected to last for a good many years, but most new home owners usually don’t put too much thinking into what their telecommunications, video, audio, security and building monitoring requirements are today, let alone what might be needed in 5, 10 or 20 years. Installing plenty of cabling and jackpoints today in unlined walls (whether it is Cat 5 or RG6 co-axial cable) incurs far lower costs than adding cabling and jackpoints in a completed home. In view of this, it pays to provide the flexibility to meet a range of future needs, and not base cabling provision only on what is thought to be needed today. In the past 20 years or so, most customers have moved from having “one telephone in the hall” to multiple phones, a fax, and one or more PC’s sharing ADSL services for internet, email, etc. Similarly, one TV set (probably monochrome) has progressed to two or more colour TV sets, VCR’s and DVD players or recorders, all of which could be networked together in a modern home. What is going to come up in the next 20 years, who knows? 5. NZ RELAY SERVICE: TTY – 027 HANDSET COMPATIBILITY The introduction of the NZ Relay Service for deaf and hearing-impaired users late last year raised the issue of mobile network support for TTY users. While carrying slow 50 Baud TTY signals over a modern mobile network might seem at first sight to be a minor technical problem, it has proved to be a lot more complex. Digital networks “chop up” the relatively long duration TTY signal tones into as many as 12 separate signals and are simply not designed to carry the single frequency tones used by TTY’s, as the cellphone’s complex encoding systems are optimised for voice operation. While mobile handsets connected to our old analogue 025 network should be satisfactory with TTY’s, we are not encouraging its use because it is due to be phased out in a few years. Our testing of the 027 network has shown that the network itself will carry TTY traffic, but not all TTY’s and cellphones are actually compatible. Most 027 handsets use the Qualcom chipset, which is not compatible with TTY operation. However, the following handsets supplied by Nokia (all of which use different chipsets to the majority of other 027 cellphones) have been shown to work with the DSPG 9100M TTY (which is the model which the NZ Relay Service is expected to be providing to its clients). Nokia 2280 Nokia 3585 Nokia 3586 Nokia 6015 Nokia 6585 Nokia 6225 Nokia 6255 WARNINGS The 9100M TTY is the only TTY we have tested so far that works with these 027 handsets. For compatibility, this particular TTY needs to be operated in “Mobile” mode, not “mobile Baudot”. No other TTY model nor any other 027 cellphones should be expected to be compatible when used over the Telecom 027 network until the specific combination has been formally tested. Many hearing-impaired mobile users are likely to prefer SMS or email for a lot of their calls, but because the NZ Relay Service provides a valuable link between users of these services and PSTN customers who have only standard telephones, we will keep an eye out for further handsets and TTY’s that can operate in combination over our 027 network. This includes support for calls to and from the NZ Relay Service, as well as directly calls between users with the right combination of TTY and 027 handset. 6. CELLPHONE “JAMMERS” Another topic which generates questions from time to time is that of cellphone “jammers”, devices which are intended to prevent the use of cellphones in a specific area, such as a concert hall or cinema. The unauthorised use of “cell phones” by those on custody (pun intended) is another matter that has received some publicity recently. Despite the point that “jammers” may seem desirable in some circumstances, they may not be used in either New Zealand or Australia. Telecom’s position was outlined in Newsletter No. 141, but further questions led to the matter being addressed more formally by the Radio Spectrum Management group of the Ministry of Economic Development, who were kind enough to permit my publication of the main points of their ruling in this newsletter. The following excerpt includes some minor editorial changes to “generalise” the response that was given for a specific enquiry:- “Any use of cellphone “jammers” impacts on the legislative provisions for radiocommunications (the Radiocommunications Act 1989 and the Radiocommunications Regulations 2001) which the Ministry administers.   Individuals in New Zealand (and all other countries signatory to the International Telecommunications Union conventions) do not have "rights to regulate their own airspace". New Zealand requires that any transmission of radio waves may only be made in accordance with an authorising licence, or in accordance with a specific exemption from having such a licence.   Licences for use of a transmitter in the cellular phone frequencies in NZ can only be registered by the organisations (Telecom and Vodafone) holding the management rights for those frequency bands. No licences have been issued for operation of jamming devices, and the Ministry's communications with those organisations to date indicate that they do not intend to create and register such licences. In view of that approach, and considering the risk to emergency communications which might result from jamming equipment, the Ministry has not issued any exemption from licensing for such devices.   The supply of radio transmitters in New Zealand requires the supplier to hold a licence to supply, and it is only legally permissible to supply radio products which meet both applicable radio Standards, and licence conditions. As no licences have been issued for cellphone “jammers”, these devices must not be supplied in New Zealand, nor may they legally be used.   The Radiocommunications Act provides for significant penalties of fines of up to $30,000 for an individual, or $200,000 for a body corporate if convicted of an offence.”   Anyone interested in pursuing the issue of using or supplying cellphone “jammers” to the local market should access and read http://www.med.govt.nz/rsm/standards/index.html#information-for-suppliers and http://www.med.govt.nz/rsm/licensing/index.html  which are published on the Radio Spectrum Management web site, under "Standards & Compliance". A more acceptable means of dealing with the disruptions that can be caused by cellphones is the use of a detector, which simply indicates that a cellphone is turned on even when it is not actually in use. This allows the “management” of the location in question to make sure that all cellphones in the vicinity have been turned off and will not cause disruption. If used in conjunction with signage asking that all cellphones be turned off and warning that detectors are in use, all but the more determined user will usually comply with the request. Doug Burrus Manager Access Standards