PSTN, WAN and Cable/Phone company

hendychow

Hi All,

Is there anybody could answer my questions :
1. When I read the CVOICE book, there are 2 connections that are used to make a call, which are
PSTN and WAN.
What's the difference between PSTN and WAN ?
Are they both provided by service provider ? PSTN = Phone company. WAN = ISP Company ?

2. There are some cable companies such as Comcast, Verizon, Time Warner, etc
The examples of the services that they offer are Cable TV + phone +Internet
My question is :
Are those services using Voip Technology or just Digital ?
I am still confused differentiating between Digital and Voip Technology. Please suggest.


Thank you very much


Marius

Deadmaster200

For testing purposes, keep the PSTN and the WAN as two completely separate entities. PSTN is a separate network that was built for the sole purpose of providing telephone service, WAN networks exist to provide data networking services. In reality, yes, it is all one big network. As the book itself says, major service providers have been converged for years, but they didn't really 'converge' as it just developed the way it is naturally.

As far as phone service goes, the difference between analog and digital is simply the method of transmitting human voice over a medium (copper). Analog is the old and original way, like how a microphone works. Your voice is converted into an analog signal and sent over the wire as is. Digital came along to deal with noise, distance limitations, and to enable multiplexing (which if this never happened, the PSTN would never have been able to provide the data services we are familiar with (T1 and so on). Your voice is processed by a computer so that your analog voice can be described with digital bits. That is all digital means and existed LONG before VoIP.

Also, don't get confused about the term VoIP itself. VoIP is just a subset of IP Telephony. VoIP is misused to mean IP Telephony itself. VoIP is the method of taking a traditional PSTN signal and first digitizing it, and then encapsulating that digitized voice into IP packets for use in an IP network. IP Telephony is the concept of an end-to-end packet network providing telephone service. No PSTN-to-IP conversions, no traditional phones. Requires IP phones and other IP telephony versions of PSTN equipment, like gateways, gatekeepers, Cisco Call Manager instead of PBXs and phone switches. However, this only applies to the network under your administrative control. You still have to have VoIP at the edge of the network to communicate with the outside world (at least until IP Telephony completely replaces the PSTN globally which may happen, eventually).

hendychow

Hi All,

I need help

Refer to the CVOICE book by Kevin Wallace :

1. I am wondering why sometimes T1 was used to connect to PSTN, sometimes just PSTN
Router

---

PSTN
OR
Router

---

T1

---

PSTN
Which one is correct ?

2. What is the purpose of FXS / FSO port in a Router ?
It did not explain literally on the book.
I only can summarize that the purpose is to convert Analog to Voip network.
Is this right ? Please suggest.

3. In a Voice enabled Router Router :
FXS = Connect to Station
FXO = Connect to Office

Why does sometimes "FXS port connect to PBX" and sometimes "FXO port connect to PBX" too ?
Is it because It depends on the function of PBX ?

4. In POTS dial peer, which port is used ? FXS or FXO ?


Thanks


Marius

dtlokee

mariusac wrote:

Hi All,

I need help

Refer to the CVOICE book by Kevin Wallace :

1. I am wondering why sometimes T1 was used to connect to PSTN, sometimes just PSTN
Router

---

PSTN
OR
Router

---

T1

---

PSTN
Which one is correct ?

2. What is the purpose of FXS / FSO port in a Router ?
It did not explain literally on the book.
I only can summarize that the purpose is to convert Analog to Voip network.
Is this right ? Please suggest.

3. In a Voice enabled Router Router :
FXS = Connect to Station
FXO = Connect to Office

Why does sometimes "FXS port connect to PBX" and sometimes "FXO port connect to PBX" too ?
Is it because It depends on the function of PBX ?

4. In POTS dial peer, which port is used ? FXS or FXO ?


Thanks


Marius

1. I am not sure what the question is, I do not have the book you're talking about.

2. They are both used to connect to analog devices, yes they convert digital to analog and analog to digital as you said. FXS connects to an end devce so therefore it is used to receive dialed digits and make connections to the end station based on a dialed number from remote devices, but it only connects to one device. The FXO is used to connect to the PSTN or a PBX and can send digits to the PSTN and receive incomming calls.

3. The use of the FXS and FXO can vary depnding on the way the VoIP network is connected to the PBX. Some PBX (or other type phone systems) will have several connections that are designed to be connected into the PSTN (the interface is basically a FXO interface on the PBX) so to connect this to our voice network we would use a FXS interface on our router. On the other hand if we are connecting to a PBX FXS interface we woud use a FXO on the router.

4. Can be both

hendychow

dtlokee wrote:

1. I am not sure what the question is, I do not have the book you're talking about.

2. They are both used to connect to analog devices, yes they convert digital to analog and analog to digital as you said. FXS connects to an end devce so therefore it is used to receive dialed digits and make connections to the end station based on a dialed number from remote devices, but it only connects to one device. The FXO is used to connect to the PSTN or a PBX and can send digits to the PSTN and receive incomming calls.

3. The use of the FXS and FXO can vary depnding on the way the VoIP network is connected to the PBX. Some PBX (or other type phone systems) will have several connections that are designed to be connected into the PSTN (the interface is basically a FXO interface on the PBX) so to connect this to our voice network we would use a FXS interface on our router. On the other hand if we are connecting to a PBX FXS interface we woud use a FXO on the router.

4. Can be both

1. What I mean is that how to connect to PSTN ?
Is it by using a T1 line connected to our router's FXO port ?

Voice enabled Router --Fxo port

---

>T1

---

> PSTN

2. FXO / FXS ports are used to convert VOIP TO ANALOG or ANALOG to DIGITAL ?

By connecting the router's FXS port to analog phone &
connecting the Router to Voip Network/Call manager,
we can make a call from Voip phone to that analog phone.

Is this correct ?

Thank You