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ISDN Limitations ?!?!
- Thread starter oudmaster
- Start date
Solution
Someone Somewhere
Titan
- Sep 23, 2012
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Because there's a limit on what can be moved over the spectrum allocation assigned to ISDN. Plus, it's thoroughly standardised. Meaning that you can't just change bit of it, because you break interoperability.
ISDN isn't used much, and people are trying to get off it to more modern means where possible.
ISDN isn't used much, and people are trying to get off it to more modern means where possible.
ISDN is still commonly used for voice traffic between pbx devices in many countries. It can go more than 2m. The 2m limitation is mostly if you try to use it for data. It just gets very messy to use larger circuits like ds3 that are running ISDN for data.
ISDN always was a technology based on the voice infrastructure similar to modems. It never was the best way to do it but when your only option to get a circuit was to pass through a bunch of voice switches you use what you can get. The next step up was actual dedicated circuits where you could avoid having to deal with voice signalling and pass raw data. Now days it is all virtual you really don't know what you are really running on. If you were to order ISDN service it likely would be emulated over a IP network in many cases once it got to the central office.
ISDN always was a technology based on the voice infrastructure similar to modems. It never was the best way to do it but when your only option to get a circuit was to pass through a bunch of voice switches you use what you can get. The next step up was actual dedicated circuits where you could avoid having to deal with voice signalling and pass raw data. Now days it is all virtual you really don't know what you are really running on. If you were to order ISDN service it likely would be emulated over a IP network in many cases once it got to the central office.
Someone Somewhere
Titan
- Sep 23, 2012
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Yup. Even phone services are converted to ATM or IP the moment they hit the exchange.
These days people usually run SIP or H.323 over the IP network instead of using dedicated lines like ISDN. You just move all your telephony and VC systems over your internet connection. As you need a good upstream, this would probably be fibre or SHDSL/VDSL.
These days people usually run SIP or H.323 over the IP network instead of using dedicated lines like ISDN. You just move all your telephony and VC systems over your internet connection. As you need a good upstream, this would probably be fibre or SHDSL/VDSL.
Someone Somewhere
Titan
- Sep 23, 2012
- 22,291
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You'd need a business grade fibre for that, through your ISP's network to the other end.
1000BASEZX can do ~70km, and you could put a repeater in the middle. You'd need to dig your own trench for that, though.
Ultra-directional microwave dishes on towers could do it, too.
1000BASEZX can do ~70km, and you could put a repeater in the middle. You'd need to dig your own trench for that, though.
Ultra-directional microwave dishes on towers could do it, too.
Someone Somewhere
Titan
- Sep 23, 2012
- 22,291
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What? A PBX is a Private Branch eXhange, i.e. a telephone exchange you own.
1000BASEZX is a spec of Gigabit Ethernet over single-mode fibre. You'd need to lay your own fibre, probably.
1000BASEZX is a spec of Gigabit Ethernet over single-mode fibre. You'd need to lay your own fibre, probably.
It depends on your PBX. Many large ones are very similar to central office switches. You could technically hook to them and they can allow data connection to pass but there is not a lot of good reason to be actually hooking them to the PBX when you need data. I guess if you had a huge number of voice calls between 2 PBX using the older signalling method and wanted to carry data over the same circuit you would use the PBX to do this.
You can still buy these circuits and if you need to go very long distances...ie between cities or countries...at very high speeds. You would buy a oc-12 (622m) or oc-48 (2.4g). These still require a fiber connection directly between your building and one of the telco offices. It would then be carried over the telco network to a similar fiber on the far end.
Unless you are passing voice the older way or have a need for extremely accurate clocking provided they are not worth the cost. Once you have a fiber to your premise from the telco office there are better data options like MPLS networks for obtaining connections, the first connection from your building to the telco could still be oc-xx but it is generally hidden from you by the telco,
You can still buy these circuits and if you need to go very long distances...ie between cities or countries...at very high speeds. You would buy a oc-12 (622m) or oc-48 (2.4g). These still require a fiber connection directly between your building and one of the telco offices. It would then be carried over the telco network to a similar fiber on the far end.
Unless you are passing voice the older way or have a need for extremely accurate clocking provided they are not worth the cost. Once you have a fiber to your premise from the telco office there are better data options like MPLS networks for obtaining connections, the first connection from your building to the telco could still be oc-xx but it is generally hidden from you by the telco,
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