Remote Telephone Extension

Problem
You have a remote office connected over a T1 to your headquarters. Perhaps your primary application is data or you don't have PSN access at the remote site. Either way, it is more cost effective to use your open PBX extensions over the T1 than it is to order up a separate circuit. A standard FXO to FXS telephone extension will meet your requirements.

Solution
Coastcom's combination of 2-Wire FXS and 2-Wire FXO channel cards can provide a telephone extension from your PBX to the remote location.

How Does It Work?
Both cards are transparent and are extending the connection from the PBX to the telephone. The remote end caller is effectively connected to the PBX in the same manner as a near end caller.

Figure v9. Standard FXO/FXS Telephone Extension

What Actually Occurs?
The call sequence is dependent on whether you're set-up for ground start or loop start signaling. Loop start signaling is preferred in this situation because you are connecting directly to the telephone with the FXS card. The following sequence assumes loop start signaling.

Celia works in the remote office, she decides to make a call to a vendor. She picks up the phone (off-hook) and dials her access code for an outside line (typically a 9). The PBX signals the near end CO by closing the loop. Closing the loop causes current flow between the PBX and the CO. The CO sees the current and replies by sending back a dial tone.

Celia dials the vendor's telephone number. The PBX sends the digits to the near end CO which proceeds to make the connection through the PSN.

The PSN routes Celia's call to the vendor through the far end CO. The far end CO rings the vendor's phone. Celia hears a separate ring back from the far end CO.

When the vendor answers the call the far end CO signals back through the PSN to the near end CO/PBX. When the call is complete, Celia hangs up (on-hook), the current flow stops, and the circuit is disconnected.

How Do You Set It Up?
Both the FXS and the FXO channel cards are set-up in their standard modes with loop start signaling.

What Do You Order?
For each telephone at the remote end you will need one FXS circuit and a corresponding FXO circuit for connection to the PBX. The FXS channel cards come with either two circuits per card called a Dual, or four circuits per card called a Quad. The FXO channel cards each have two circuits. So you'll need to order one circuit, of each type, for every telephone extension. You will also require a D/I Mux III at each end and a ringing generator at the FXS end.

Customer Billing/Universal Voice Grade

Problem
Perhaps you are a hotel owner or you just need to keep track of outgoing toll calls. You have a PBX connected over T1 to an EO where the local carrier is providing you with 2-Wire lines. You need to track the outgoing toll calls in order to bill your customers. Universal Voice Grade with Reverse Battery will fit your needs.

Solution
Coastcom's 2-Wire FXS channel cards offer UVG mode with RB support.

How Does It Work?
The FXS card in UVG mode with RB support lets the PBX know when a call is connected, so that the PBX can track the duration of the call. This is similar in concept to a stop watch. The PBX is the timer, the application of the RB is the action of starting the timer, and the removal of the RB is the action of stopping the timer.

Figure v10. UVG Extension to PBX

What Actually Occurs?
The FXS channel card in UVG mode can automatically sense the signaling type. It will operate in either ground start or loop start dependent on the configuration of the line and it will automatically apply RB when required. UVG is commonly used with CSA loop lines. In the application described below ground start in conjunction with RB is assumed.

Joe owns a motel. He wants to offer his customers long distance service and he wants to add a surcharge to defray the associated costs.

Joe's customer, Ann decides to make a call to her sister Sally in another state. She picks up the phone (off-hook) and dials her access code for an outside line (typically an 8 or 9). The PBX/UVG signals the far end CO by applying ground which causes current flow between the PBX/UVG and the EO. The EO sees the ground and replies by applying ground on a second wire. It then sends back a dial tone.

Ann dials the telephone number. The PBX sends the digits to the EO which proceeds to make the connection through the PSN. The PSN routes Ann's call to Sally's home through the far end CO. The far end CO rings Sally's phone.

When Sally answers the call the far end CO signals back through the PSN to the near end EO/PBX. The near end EO signals to the PBX/UVG that the call connected. The UVG applies a reverse battery and the PBX management system starts the call timer.

How Do You Set It Up?
The FXS and FXO channel cards are set-up in UVG mode. When UVG is selected the signaling mode is automatically selected by the FXS channel card. UVG mode requires that both ends of the circuit be Coastcom equipment.

What Do You Order?
Typically this is a service that would be owned and provided by an RBOC, however it is possible for a customer to own all aspects of the network. In that situation the

D/I Mux IIIs could be co-located. For each telephone connection you will need one FXS and one FXO circuit. The FXS channel cards come with either two circuits per channel card called a Dual, or four circuits per channel card called a Quad. The FXO channel cards are Dual. So you'll need to order one of each circuit, at each end, for every telephone connection. You will also require a D/I Mux III at each end and a ringing generator at the PBX end.

Direct Inward Dial Extension

Problem
You have a campus environment with a private network connecting to the PSN. You are receiving 2-Wire DID circuits from the local phone company's CO. You want to extend the connection to a PBX at a remote site over a private T1. You have a main number, but each individual in your business has a four digit extension which requires direct inward calling access from the outside without switchboard intervention.

Solution
Coastcom's 2-Wire FXO channel cards in LRB/DPT mode offer the signaling states required to interface Direct Inward Dial (DID) services on a LRB line. Coastcom's 2-Wire FXS extends the DID services by offering a CO connection over T1.

How Does It Work?
With a DID circuit the CO is operating the inverse of its normal operation. The CO usually receives digits from the customer (subscriber). In DID the CO sends digits to the subscriber. The FXS and FXO cards are basically transparent and are extending the connection from the CO to the PBX much as an extension cord provides power from the outlet to your appliance. The CO is the outlet and the appliance is the PBX.

Figure v11. Configuration for DID Extension Services

What Actually Occurs?
An outside caller dials the seven digit telephone number to your business in order to speak to Ann. The first three digits for each individual is the same. For example Ann's number is 777-1234 and Joe's number is 777-1235.

When the CO receives the seven digit number it signals through the FXS/FXO to the PBX to seize the line. The PBX prepares to accept the 4 digit extension number from the CO.

If Ann is free (on-hook), the PBX signals back with a LRB wink (temporary battery reversal) to the CO. The CO passes the four digit access number to the PBX. The PBX rings Ann's extension.

When Ann picks up (off-hook), the PBX applies a LRB (held during call) back to the CO and holds it. The CO starts billing upon receiving the second LRB.

When Ann finishes her call and hangs up, the PBX turns off reverse battery and the CO discontinues billing.

The Direct Inward Dial feature works on incoming calls only. If Ann wants to call out, she dials a special access code, 9 for instance, which tells the PBX she wants an outside line. She is using a different circuit type for outgoing calls. A T1 provided by the CO can contain multiple circuit types.

How Do You Set It Up?
Both the FXS and the FXO channel cards are set-up in LRB mode. The FXS is set for DPO. The FXO is set for DPT.

What Do You Order?
For each DID trunk from the CO you will need one FXS circuit and a corresponding FXO circuit for connection to the PBX. The FXS channel cards come with either two circuits per channel card called a Dual, or four circuits per channel card called a Quad. FXO channel cards each have two circuits. So you'll need to order one circuit, at each end, for every telephone extension. You will also require a D/I Mux III at each end. A ringing generator is not required at either end because the PBX is generating ring.