Telephone Line Connection Information
When developing a product to be connected to the telephone line, it is necessary to use a circuit known as a Data
Access Arrangement (DAA) approved by the appropriate governmental agency. In the US this agency is the Federal
Communications Commission (FCC), while in Canada it is Industry Canada (IC). In Europe the CTR21 standard
covers all countries in the European Union. These agencies test and approve the product to ensure that it meets their
specifications, thereby protecting the telephone system from damage and protecting the user from high voltage
transients (such as lightning strikes) which may come down the telephone line.
The XEV90C has been designed to meet all FCC Part 68 requirements for hazardous voltage, line impedance and
leakage current. If the system transmits data, synthesized voice, or DTMF tones on the telephone line, the user must
certify that the signals transmitted meet basic FCC requirements for maximum transmission levels, out of band energy
and billing delay. Full details may be obtained from the FCC under Part 68 of the FCC Rules and Regulations, or in
Title 47 of the Code of Federal Regulations, however the basic requirements are as follows:
1. Maximum Transmit Level
For the normal “permissive” (standard) telephone line, equipment which transmits data (such as a modem) must not
exceed a transmission level of -9 dBm.
2. Out of Band Energy
Data equipment must not transmit “out of band” energy on the telephone line which exceeds the following limits:
Frequency
Range Max. Power
3995 Hz to 4005 Hz -27 dBm
4005 Hz to 12 kHz -20 dBm
12 kHz to 90 kHz -55 dBm
90 kHz to 270 kHz -55 dBm
270 kHz to 6 MHz -15 dBm
3. DTMF Transmission Level
If the system is capable of DTMF dialing, the maximum DTMF transmission level must be less than 0 dBm averaged
over a 3 second interval.
4. Billing Delay
A delay of 2 seconds or greater is required after the time the XEV90C is taken “off hook” and before any information
is transmitted. This is required to ensure that billing information may be exchanged between telephone company
central offices without interference.
OEM’s using the XEV90C must certify to the FCC that the final system meets the requirements of Part 68 which
include the criteria above as well as the high voltage protection provided by the XEV90C. This is generally
accomplished through an independent testing lab which tests the System and submits the proper paperwork to the FCC
for approval. Since the XEV90C already complies with FCC Part 68 rules, this is a relatively simple process.
XECOM
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XEV90C