Can a DS3 be split to provide internet access and a certain number of channels for voice?

childersj used Ask the Experts™
We are looking at options for bandwidth and are considering a DS3 for next year.  I'd like to get rid of our PRI T1's.  Would it be possible to (going on the assumption that our ISP offers this package) split the DS3 partially for data and partially for voice to replace some PRI T1's?

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We have 2x T1 (DS1) that are split this way dynamically.  Every time the PBX grabs an outside line, it takes the channel bandwidth away.  When the call is hung up, the channel/bandwidth is released.

The voice calls take priority, so you need to provision so that your normal or peak call volume does not kill the available bandwidth.

Your PBX should have average volume and peak volume broken out per hour.  Peaks for us are at 8am, 1am (after lunch), then 4pm before close of day.  If you average at 20 lines, then expect a full T1 equivalent bandwidth will be lost.  If you peak at 60...look at your bandwidth consumption to see if that's an issue.

To be safe, we threw a 9Mbps ADSL line on the router for load sharing.  Dump a lot of the internet and guest WLAN traffic to that.

Yes, XO communication is providing me a DS3 with voice and data. You just tell them how channels you want for voice.

If the DS3 is delivered on SONET into your premises then it can in theory be broken up into 28 T1, and you can use one of those for your voice traffic.

The only issue is how to use the remaining 27 T1 in an effective way without spending too much on equipment - both in your premises and at the provider side. The most economical way is usually if the provider have equipment that can do Ethernet-over-SONET, and so they can present you with a FastEthernet interface of almost 45Mbps (plus that voice T1).
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I thought that DS3 could also be channelized (integrated voice & data) similart to DS1.  Ours breaks off bandwidth one voice channel at a time, then releases back to max out at 2xT1 speeds.

A DS3 (actually T3) can be broken down into 28 T1, and each T1 can be broken down into 24 voice channels (56kbp ot T0).

When working with T0s you would probably use multilink PPP as layer 2 protocol. Should be possible...

Still, for this case, if they have 27 T1 for data, it is not worth messing with adding T0s too.


Broadview said that it is possible to sell the service this way if they put in an multiplexer.  They have done this, but it isn't a standard offering.  It would have to be a special contract and approved by who ever reviews contracts in their provisioning team.
That makes sense. In reality they need multiplexing on both your side and theirs.

It may make sense to plan ahead and buy something that can be used in the next upgrade. They could install an OC-3 (155Mbps) into your site, and get a multiplexer that can break out both a T1 (for you PBX) and a channalized T3 (for your router).


I wasn't trying to cancel this.  I was trying to award points.

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