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> Digital voice services, which are basically VoIP You say that as if things like GR-303 and ISDN BRIs/PRIs don't exist. The only thing that isn't digital abou

> Digital voice services, which are basically VoIP You say that as if things like GR-303 and ISDN BRIs/PRIs don't exist. The only thing that isn't digital about modern, non-IP phone networks is the last mile when you order an analog loop. > properly differentiate between calls and data, so calls on these networks are going to be much more reliable than simply leasing a SIP trunk. In theory, sure. As I said though, in my experience the vast majority of these routes tend to fall behind their circuit switched counterparts in performance even on carrier grade routes.

jallmann 11y ago
> You say that as if things like GR-303 and ISDN BRIs/PRIs don't exist. Granted, "digital voice" was imprecise terminology, but you get the gist... modern consumer phone services are VoIP. > fall behind their circuit switched counterparts in performance even on carrier grade routes. Most carrier backbones have been all-IP for years. Pretty sure end-to-end circuit switched calls are atypical nowadays, although I'm happy to be proven wrong.
- pastycrinkles 11y ago
  > Most carrier backbones have been all-IP for years. Pretty sure end-to-end circuit switched calls are atypical nowadays, although I'm happy to be proven wrong. That certainly depends on what network and where. If you're talking about someone like Level 3, they definitely use IP transport for phone calls. But there's a number of networks that don't. Verizon, for example, has a toll network based on the DMS-250 and DEX-600 switch platforms. Both of these are designed from the ground up to handle circuit switched traffic. There are a few routes that're IP, but they're pretty easy to pick out since there's a combination of comfort noise, significant latency and packet loss (!) on them. AT&T, similarly has a toll network running on 4ESS, 5ESS and DMS-250s. There are a few IP trunks on there, but they're typically only used for destinations like San Francisco to Chicago. Sprint has an all DMS-250 network at their disposal as well, as well as TDS Metrocom and the McleodUSA network that Windstream bought. Anyway, you get the idea. On the local end, to get transport to the phone network, you have to order DSX trunks; there is no IP trunking to be had. Not to mention, there's typically quite a large number of circuit switches in any given market. Typically enough to outnumber the number of softswitches.
  - jallmann 11y ago
    Very interesting, thanks for the information!

jallmann 11y ago

> You say that as if things like GR-303 and ISDN BRIs/PRIs don't exist. Granted, "digital voice" was imprecise terminology, but you get the gist... modern consumer phone services are VoIP. > fall behind their circuit switched counterparts in performance even on carrier grade routes. Most carrier backbones have been all-IP for years. Pretty sure end-to-end circuit switched calls are atypical nowadays, although I'm happy to be proven wrong.

pastycrinkles 11y ago
> Most carrier backbones have been all-IP for years. Pretty sure end-to-end circuit switched calls are atypical nowadays, although I'm happy to be proven wrong. That certainly depends on what network and where. If you're talking about someone like Level 3, they definitely use IP transport for phone calls. But there's a number of networks that don't. Verizon, for example, has a toll network based on the DMS-250 and DEX-600 switch platforms. Both of these are designed from the ground up to handle circuit switched traffic. There are a few routes that're IP, but they're pretty easy to pick out since there's a combination of comfort noise, significant latency and packet loss (!) on them. AT&T, similarly has a toll network running on 4ESS, 5ESS and DMS-250s. There are a few IP trunks on there, but they're typically only used for destinations like San Francisco to Chicago. Sprint has an all DMS-250 network at their disposal as well, as well as TDS Metrocom and the McleodUSA network that Windstream bought. Anyway, you get the idea. On the local end, to get transport to the phone network, you have to order DSX trunks; there is no IP trunking to be had. Not to mention, there's typically quite a large number of circuit switches in any given market. Typically enough to outnumber the number of softswitches.
- jallmann 11y ago
  Very interesting, thanks for the information!