Tieline Technologies

POTS Support

While the Tieline is a very reliable product, its performance will only be as good as the line that it’s operating over. When using a POTS line, proper precautions MUST be taken to ensure that only the Tieline codec uses the line. Please ensure that you remove these possible interference sources:

  • DSL or ADSL Modems
  • Other telephone handsets
  • Portable phone base stations
  • Unused parallel phone sockets
  • Fax machines
  • Burglar Alarm systems
  • Extension bells

Call Waiting

Call waiting tones may cause the codec to malfunction. Most phone companies supply call waiting as a feature and you will need to turn it off. In the internal phone book, program the number for disabling call waiting, and dial it before calling anyone.

Private Branch Exchanges (PBX), Private Automatic Branch Exchanges (PABX) Business Systems

Avoid connecting a Tieline codec to a PBX, PABX, Key station, business system or any other local switchboard. Easily said, the tricky bit is working out if you are on one of these systems.

As a general guide, these devices have two characteristics:

  1. Requires the dialing of an additional digit to access the PSTN (Public Switched Telephone Network)
  2. Having more buttons and features than your average space shuttle.

Warning: Some of these systems are often digital and have non standard telephone line operating voltages. If you plug a digital PABX/PBX line into a Tieline codec, permanent damage may result from the high voltage pulses these systems generate. Even if the PBX is not digital, the performance of the codec is unlikely to be as good as a normal POTS/PSTN line.

TIP: If you have no option than using a PBX/PABX, search for a fax machine. Thankfully the overwhelming majority of fax machines are designed for analogue POTS line operation and are normally on an extension optimized for fax machines and data transmission. Substitute a normal phone for the fax machine and verify correct operation. Use a normal phone, not a house supplied phone as the house phone may have characteristics to match the existing PBX/PABX, not a POTS line. After confirming correct phone operation unplug the phone and plug into the codec.

Line Checks

Length of the line from your site to the Central Office or Local Exchange
It is desirable to have a local loop (the line from your location to the local CO or
Exchange) as short as possible. Optimum performance can be expected for lines up to about 2 miles (3 kilometers) in length. Lengths in excess of this can be expected to perform at lower bit rates and line quality depending on the age, condition and type of cabling. E.g. plastic insulation, paper insulation, water or moisture entering the cable, age and state of repair of joins.

Presence of stub or party lines on your local loop:

In some countries, it was the practice to have more than one phone service attached to one line. Sometimes called a Party Line. As more lines have been installed, services have been separated but the redundant cabling may remain connected across your line and it will cause problems with operation of your Tieline codec.

As an example, a POTS service has been provided to a customer a long way from the CO, this customer has since moved on. The phone company needs to provide a phone service in the same area, but closer to the CO. Let us assume half way. The service is provided, however the phone company simply jumpered the new service onto the old (further) service. The cable from the jumpering point to the old service point is redundant, and will act as a stub, loading the line down. This will not matter for a phone service. However it will affect the performance of a Tieline codec connected to the line.

A common variation of this problem is in high rise buildings. Most high rise buildings have a MDF in the basement and a series of smaller IDFs on the floors. If a line was originally used on an upper floor would have a connection from the CO to the MDF and then from the MDF to IDF for the appropriate floor. Over time the service has been redeployed to a lower floor. However for a quick installation the Phone Company did not disconnect the upper floor IDF , they just bridged into the lower floor IDF leaving the upper floor IDF still connected. The unused stub from the lower to upper floors can cause problems.

Earth Leakage Problems on the Line

A good line should have an earth isolation of better than ten meg-ohms. If your line is located in an area where water is a problem, ask your Telco to check out the earth leakage.

Equipment Problems at the CO or Local Exchange

Although there are many factors at the Telco end that can cause problems, a
problem that does occasionally occur is if the clock on the interface codec to your
line is not synchronized to the network. A drifting clock will cause instability and
unreliable G3 performance. If you suspect that this could be the
problem, contact your local Telco .

The Tieline family of codecs is designed to achieve solid and reliable operation with a line quality of 30% or better. On most good POTS lines, the G3 will normally achieve 28,800 bps and a line quality of approximately 50% or greater. If you are not able to achieve this level of operation, you may have transmission problems with your line or the line at the other end of the connection. Using the Tieline test facility on Tips for Successful Operation
Following are a few simple and handy hints that could save you a lot of blood, sweat and tears when you are setting up your codec at a remote site:

  1. It can be a good idea to take your own phone when you are doing a remote
    broadcast. If possible dial the number you are going to use and check for any
    unusual noises. These may be due to other devices connected to the line.
  2. Tieline USA has a test unit on 317 913 6911 to facilitate testing. The
    G3 will automatically negotiate the optimal connect rate for
    each individual circuit on connection
  3. Some facilities, especially large hotels, are able to provide phone connection
    points to allow a dial-up connection for Lap Top Computers. Lap Top
    Computers use technology similar to G3 POTS codecs, so a
    Tieline codec will invariably work if the computer connection speed is
    24,000 bps or higher.
  4. Take an ADSL/DSL filter to all remote locations. ADSL/DSL modems can
    generate noise on a line which will degrade the performance of your
    G3. Due to the increasing popularity of ADSL/DSL services
    on phone lines, this is likely to be an increasing problem but one that is
    simple to solve. Simply place the ADSL/DSL filter in series with your codec
    to remove the interference.

All this obviously takes time, often requiring assistance from hotel staff, resident IT geek etc. If you have no other option than connecting your G3 to a PBX/PABX, Tieline recommends that you confirm that the line works BEFORE you try to do a live program.

Tips for Successful Operation

Following are a few simple and handy hints that could save you a lot of blood, sweat and tears when you are setting up your codec at a remote site:

  1. It can be a good idea to take your own phone when you are doing a remote
    broadcast. If possible dial the number you are going to use and check for any
    unusual noises. These may be due to other devices connected to the line.
  2. Tieline USA has a test unit on 317 913 6911 to facilitate testing. The
    G3 will automatically negotiate the optimal connect rate for
    each individual circuit on connection
  3. Some facilities, especially large hotels, are able to provide phone connection
    points to allow a dial-up connection for Lap Top Computers. Lap Top
    Computers use technology similar to G3 POTS codecs, so a
    Tieline codec will invariably work if the computer connection speed is
    24,000 bps or higher.
  4. Take an ADSL/DSL filter to all remote locations. ADSL/DSL modems can
    generate noise on a line which will degrade the performance of your
    G3. Due to the increasing popularity of ADSL/DSL services
    on phone lines, this is likely to be an increasing problem but one that is
    simple to solve. Simply place the ADSL/DSL filter in series with your codec
    to remove the interference. All this obviously takes time, often requiring assistance from hotel staff, resident IT geek etc. If you have no other option than connecting your G3 to a PBX/PABX, Tieline recommends that you confirm that the line works BEFORE you try to do a live program.

Tieline USA has a POTS test line number at: 317 913 6911