POTS Operation Precautions

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 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.

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.

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.

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[1] in the basement and a series of smaller IDFs [2] on the floors. If a line was originally used on an upper floor would have a connection from the CO to the MDF[1] and then from the MDF[1] to IDF[2] 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[2] , they just bridged into the lower floor IDF[2] leaving the upper floor IDF[2] still connected. The unused stub from the lower to upper floors can cause problems.

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.

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.