Your IP is:


V92/90 (56K) FAQ's

56K Speed Limits

AT Commands


RS-232 Info

Telecom Certs

Modem Testing Stds

Layout Guideline

Surge Protection

Common Pitfalls

Modems and VoIP

xDLS Stuff


Modem Consulting

Cool Stuff




Telecom Certifications

Floyd Kling 



Confused about Embedded Modems and Telecom Certifications?

Maybe this paper will help will help.


Can Embedded Modems Obtain Global Telecom Certification?



Here is a list of the more common certifications that may be required for PSTN (dial-up) modems.  These requirements are only for your reference, it is not 'gospel'.  Actual requirements vary greatly depending on your final product.  Some of these may be required, some optional.  Make sure to check with your Certification Agency for clarification for these and perhaps other requirements.


(This is Work in Progress)


1.  FCC Part 15 (Emissions)

Part 15 defines the amount of allowable emissions that may be generated by any electrical device. 


There are two levels: 

  • Pt. 15A for business equipment.  Less stringent than Pt.15B.

  • Pt. 15B for Residential Equipment.

If you meet Pt. 15B requirements, you do not need to apply for Pt.15A.  15B is for any equipment you might find in the home. 


Embedded Modems, since they are a component, are not required, by themselves, to meet Part 15A/B standards because they cannot generate emissions until they are plugged into the host.  It is a good idea that your embedded modem manufacturer at least test for excessive emissions on a simple platform to ensure there are no 'spikes' that could fail your final product.


All products sold in the US are required to meet this standard.  Exempt are products that contain internal oscillators below (15Khz)


This information can be found under FCC Regulations "Section 47 CFR 15" ... here is a link for you.  (CFR... aka Code of Federal Regulations)


2.  FCC Part 68 (PTT Attachment-USA)

Part 68 defines the characteristics of any product that connects to the telephone network.  You cannot connect any device to a telephone network unless you have an FCC Part 68 registration number for that device.


Embedded modems require Part 68 registration.  Embedded modems Part 68 registrations ARE TRANSFERABLE to the host system.  Meaning, if you install a Part 68 registered modem into your system, you are automatically certified if you follow the instructions of your Modem Module Manufacturer. (labeling, trace routing, etc)

Embedded modems directed for connection to telephone networks outside of the US, Canada and the EU ARE NOT DIRECTLY TRANSFERABLE... In fact, many countries do not allow Embedded Modem Modules to be connected to foreign telephone networks unless certified for that specific country, within the specific final product itself.

This information can be found under FCC Regulations "Section 47 CFR 68" ... here is a link for you.  (CFR... aka Code of Federal Regulations)


3.  DOC CS-03 (PTT Attachment-Canada)

Department of Canada (DOC) rules for connection of telephony equipment is defined by CS-03.  In almost all respects it is Identical to FCC Part 68 and Part 15.  However, the modem must be submitted for DOC testing even though it has been certified by the FCC.

An IC (Industry Canada) label is required for products that attach to the Canadian telco.

4.  CTR-21, TBR-21 and TIA-968 (PTT Attachment - EU)

"A company that wants to market a product that attached to the PSTN in Europe and some other countries, will be required to demonstrate terminal compliance to the TBR 21/CTR 21 requirements".

What is TBR 21 and CTR 21 and TIA-968?

TBR 21 is the Technical Basis for Regulation produced by the European Telecommunications Standards Institute (ETSI) in response to a European Commission (EC) mandate to harmonize standards within the European Community for telecommunications terminal equipment intended for connection to the PSTN (Public Telephone Switched Network).

CTR 21 is the regulatory mandate for terminal equipment attaching to the PSTN to conform to TBR 21 and is adopted by the national governing bodies of the EC members.

Comparison of TBR 21 requirements to those for FCC Part 68 and TIA-968:

While any requirements almost the same in most cases, some limit are slightly different (more strict) for TBR 21. Additionally, where TIA-968 focuses solely on preventing terminal equipment from harming the PSTN, TBR 21 does that but also establishes requirements for minimum functional performance, for example: ringer sensitivity, DTMF frequency and inter digit timings. TBR21 does not require terminal equipment to survive the environment electrical surges required by TIA-968.


Status of CTR-21


Most European countries have adopted CTR 21 as their only national requirement for attaching terminal equipment to their PSTN.  All the countries in the EU will accept an embedded modem that complies with CTR-21 and CE. 


Depending on the country, the product may need to meet additional requirements and/or testing before it can be connected to the PSTN. For instance, some countries additional requirements apply only to products that use dial pulse address signaling. In other countries, limitations on sending levels are more stringent due to the lack of gain control within the PSTN network and the potential harm to the network if the sending levels exceed these limitations. Most modems will easily adhere to these requirements.

5.  UL1950 and UL60950-1 (Safety)

UL's new standard for some products safety UL60950-1 became effective in April, 2003. It replaced the older UL60950, which was published back December 2000. The UL60950 and the new UL60950-1 where developed for the purpose of more closely meeting the requirements to IEC60950, which is a global standard used by many countries. The old UL1950 was replaced by the first UL60950 standard for all newly developed products, but due to numerous changes to UL60950 (third edition), it has been upgraded to UL60950-1. This new UL60950-1 (First Edition) is based on the global IEC 60950-1 (First Edition).

If you are selling your products abroad, these new changes will allow your products be more easily certified/recognized by European safety agencies, and reducing the time to sell your products into the international markets.

6.  CE Marking (Safety)

CE Marking on a product is a manufacturer's declaration that the product complies with the essential requirements of the relevant European health, safety and environmental protection legislations, in practice by many of the so-called Product Directives.

  • CE Marking on a product indicates to governmental officials that the product may be legally placed on the market in their country.
  • CE Marking on a product ensures the free movement of the product within the EFTA & European Union (EU) single market (total 28 countries), and
  • CE Marking on a product permits the withdrawal of the non-conforming products by customs and enforcement/vigilance authorities.

For the most part, obtaining CE certification is not too difficult.  Submit your product to an authorized laboratory and they will take you through the gauntlet.  There are required tesing for compatibility, emmissions and safety that must be tested and documented.  There are also marking and statement requirements on labels and manuals but these are mostly a documentation issue.


7.  NEBS (Telco Equipment Standard) Network Equipment Building System

NEBS requirements take certifications to a higher level.  NEBS covers a larger range of requirements including, safety, protection of property, and higher operational standards. 


NEBS is not required for attaching your equipment to the telephone network.  However, Telcos may require that certain equipment they install in their plants be compliant to some NEBS specifications. This means, if you are going to sell your equipment to one of the TELCO carriers, you should look into any NEBS Certs they may require on your equipment.


The requirements specific to your product depends on the category it falls into.  If you have a PSTN modem, if there is a requirement, it would probably be under one of these three Telcordia Technologies (formerly Belcore) standards .

  • GR-63-CORE  Requires that all polymeric materials, components, and interconnect wire and cable used within equipment assemblies comply with certain UL flammability requirements.
  • GR-1089-CORE  Defines electromagnetic compatibility and electrical safety for network telecommunications equipments.
  • GR-487-CORE, Issue 2, Generic Requirements for Electronic Equipment Cabinets, replaces Issue 1. GR-487-CORE outlines the Telcordia view of proposed generic requirements for electronic equipment and broadband cabinets.

Passing NEBS could be an arduous task.  Regarding the modem portion, it could be as simple as adding PTC (resettable) Fuses (3A/600V) in series with TIP and another in series with RING.  The exact needed components to add to your modem will depend on what protection you modem already has (Probably very little) and the exact NEBS requirements needed.

The 3amp fuses are not too friendly to the modem but helps with NEBS. A more 'modem friendly' way may be using lower current fuses.

It is possible to minimize the component count and still protect the modem with a single 275V Sidactor (Teccor P3100EB or equal)  across T/R <on the modem side> and two polyfuses rated at .15a (Raychem TR600-150 or equal) in series with tip and one in series with ring <on the line side> .  Again, this will depend on the modem, but this has passed NEBS on some systems.

Other successes report acquiring GR-1089-CORE by the simple addition of 2ea Raychem Circuit Protection PolySwitch's - TSM600-250 (600V 250ma). You can read about it here.


8.  IEC-60601 Safety standards for Medical Devices

IEC-60601 is a series of standards containing the requirements concerning basic safety and essential performance that are generally applicable to medical electrical equipment. These requirements may be supplemented or modified by the special requirements as part of or a particular standard for certain types of medical electrical equipment.

  • IEC 60601-1 is the safety standard and defines the general requirements for electrical medical products.

  • IEC 60601-1(ed2) is the second edition of the safety standard

  • IEC 60601-1-2 is the EMC standard for emissions and immunity.


While IEC 60601-1 is not specifically for modems, being an electrical device, modems would come under this standard when used inside (or packaged with... i.e. USB External) a medical device. Even though a modem may be individually tested <and passed> for IEC 60601-x, the final system (product + modem) would probably need to be tested together to fully satisfy this requirement.

A worthwhile read on the evolution of standards.


Here is some helpful information from CCL in Salt Lake City, Utah (posted 12/06)


Communication Certification Laboratory
1940 West Alexander St
Salt Lake City, UT 84119

Tel: 801.972.6146
Fax: 801.972.8432

Telecommunications Testing for North America

In the United States, the telecommunications testing requirement is the TIS-968-A standard and the FCC Part 68 standard. The majority of the telecommunications requirements are in the TIA-968-A standard however, some requirements are still in FCC Part 68. In the USA the Administrative Council for Terminal Attachment (ACTA) administers the telecommunications testing. In Canada the telecommunications testing requirement is the Industry Canada CS-03 specification

Telecommunications Testing For Japan

In Japan, the Japanese Approvals Institute publishes the telecommunications testing requirements for Telecommunications Equipment (JATE). JATE publishes the technical requirements for both equipment that connects to the public switched telephone network and to private or leased lines. The old common name for the technical requirements is the Blue and Green Books.

Telecommunications Testing For Singapore

The telecommunications testing requirements are published by the Indo-Communications Development Authority of Singapore (iDA Singapore). For equipment that connects to the public switched telephone network the standard is iDA TS PSTN 1. For equipment that connects to the digital network the standard is iDA DLCN 1.

Telecommunications Testing For Europe

The European Telecommunications Standards Institute (ETSI) is an independent, non-profit organization, to produce telecommunications standards. Based in Sophia Antipolis (France), the European Telecommunications Standards Institute (ETSI) is officially responsible for standardization of within Europe. These technologies include telecommunications, broadcasting and related areas such as intelligent transportation and medical electronics. Popular ETSI standards are TBR 12, TBR 13, TBR 21, and TBR 38.

Telecommunications Testing For Hong Kong

In Hong Kong, the Office of the Telecommunications Authority (OFA) operates a Hong Kong Telecommunications Equipment Evaluation and Certification (HKTEC) scheme. The technical requirements are published in documents in the HKTA series issued by the Telecommunications Authority. Common HATA standards are 2011, 2017, and 2023 for analog and digital equipment.

Telecommunications Testing For Australia

In Australia, the telecommunications testing requirements are mainly located in the Australia Communications Authority (ACA) S002 standard. Depending on the equipment type, ACA S003, ACA S004, or other ACA standards might apply. The telecommunications testing in Australia is self declaration process.

Telecommunications Testing For New Zealand

The telecommunications testing requirements for New Zealand are published by Telecom New Zealand. The Telecom New Zealand scheme is call Telepermit. The most common standard is PTC 200: Requirements for Analog Telecommunications Equipment. Other standards are published for digital equipment.



Copyright © 1997-2011 Floyd Kling 
- All Rights Reserved -