Business Telephone System questions

wilson_1234_2 · ‎04-18-2007

I have some questions that maybe someone can help me to understand:

1. In a business telephone system, is the PRI that is used the same as an ISDN PRI?

2. If so, is it exactly the same?

3. One a PRI, is there one channel per phone call, so you have a maximum of 24 phone calls per PRI?

4. How does the telephone system get the phone call outside the building to another caller?

5. If you have a DID line and want to FAX sensitive documents, is it secure? Should it be encrypted?

6. What does it mean when someone becomes a POP?

Tommer Catlin · ‎04-19-2007

Hellow and welcome!

1. Basically the same. It's just easier to say PRI.

2. Yes

3. 23 channels. The 24 channel is used for signaling. So you can only have 23 possible calls going on at any one time.

4. With a Cisco Solution, you must have a router such as a 2811 with a WIC card that can plug into a PRI. The PRI comes from the local TELCO company whihc routes the DID to your PRI. Your Router is controlled by CallManager. The Router hands the digits to CallManager which then breaks the number down and matches it patterns in the system. If the pattern matches an IP Phone, it connects it to an IP phone or routes to another device or system.

5. Faxing over the PSTN has not changed since it came out in teh 1970's. Analog or digital, all phone converstations go across PSTN. (telco companies) So it is basically secure. For VOIP faxing, your network needs to be secure for voice traffic. VLANs, ACLs, COS, etc can secure your links to and from the devices.

6. Point Of Presence - POP

The physical access location interface between a local exchange carrier and an Interexchange Carrier fiber network. The point to which the telephone company terminates a subscriber's circuit for long distance service or leased line communications.

Sometimes the terms POP means the where the local carrier terminates on their network near by or down the street. The POP may serve many businesses or people in the area. Your D-Mark would be the point where it came from the POP or street, to your building and terminated. This where you would plug in your router to the PRI (at the D-Mark which is connected to the POP, then to the Telco PSTN)

Sounds like you are just getting started in Telecom.

May I suggest this book. May go over the basics what you are asking, then go into the business (callmanager, security, vmail, etc)

http://www.ciscopress.com/bookstore/product.asp?isbn=1587052571&rl=1

cheers!

wilson_1234_2 · ‎04-20-2007

Thank you for the reply.

on this answer:

4. With a Cisco Solution, you must have a router such as a 2811 with a WIC card that can plug into a PRI. The PRI comes from the local TELCO company whihc routes the DID to your PRI. Your Router is controlled by CallManager. The Router hands the digits to CallManager which then breaks the number down and matches it patterns in the system. If the pattern matches an IP Phone, it connects it to an IP phone or routes to another device or system.

follow up question:

Does the telco only provide you with one DID, or say if your company has 50 DID's, are those all provided by the telco, or do they just give you one number and the rest of the DID's are garnered from the telco provided number?

Also, I see some PRI bills that are associated to one, or even two telephone numbers. Is this a DID?

Rob Huffman · ‎04-20-2007

Hey Tommer,

Awesome answer here! I was looking at this question and didn't really know where to start.Very deserving of at least my 5 points :)

Rock-On

Rob

Tommer Catlin · ‎04-20-2007

Thanks Rob! I'm a litle bored these days...... ha