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Using VoIP service for long-distance toll bypass

Tom Lancaster explains how you can configure your PBX or VoIP installation to save you money on long-distance calling charges.

VoIP service providers offering unlimited long-distance calling for around $20-35/month have been very popular in the residential space for the past year or so, and are growing rapidly both in the number of providers and the number of subscribers. Companies like Vonage now have a lot of competition, not just from other startups but also from the former Bells, like AT&T (CallVantage) and Verizon (Voicewing). Still, most of the popular plans are restricted to residential service, but what you may not realize is that many of the smaller competitors in this space also offer a business class of service.

In this tip, we'll look at how you can take advantage of these services to act as toll-bypass for your small- to medium-sized business without converting your users to IP telephony or replacing your existing PBX.

First, from your experience with residential service, there may be many objections to overcome:

  1. Numbers are associated with lines and/or they don't offer a number in my area code.
  2. Will I still be able to do three-, four- or five-digit dialing internally?
  3. How reliable is the service? Especially over my Internet?
  4. 911 service is questionable or not available at all.
  5. How's the call quality?

If you already have either a traditional PBX or a VoIP softswitch for your office, consider the following solution: Subscribe to a company like Broadvoice, which offers a typical unlimited service for businesses for $30/month and allows you to BYOD (Bring Your Own Device). Connect a SIP gateway, such as a Cisco ATA186 to their service on the IP side via the Internet, but instead of connecting it to a phone (like you would in your residence), use it as an analog trunk to your existing PBX.

Now, configure your PBX to send calls destined for local exchanges to your old PSTN (public switched telephone network) trunks, and send all other calls (i.e. long distance) to the analog trunk first -- and if it's busy, to the old PSTN trunks. Odds are if your employees are collectively spending more than one hour per day on long-distance calls, this solution will pay for itself. If you're making overseas calls, it can pay for itself in just a couple hours per month.

Of course, you can add another line or two if you need, but let's look at the objections. First, you're using these lines for outbound long-distance only, so it doesn't matter what number they assign you. Inbound calls to your existing numbers would continue to arrive on the existing trunks. The only downside here would be the caller ID, which you could block.

Second, since you're only replacing a trunk and not replacing the users' phones, the change would be transparent to them. They'd continue to get all the features of their current PBX.

Third, you get what you pay for, so expect downtime. However, it doesn't really matter, since if the VoIP service is down, calls can simply be directed to the PSTN as if it were busy.

Forth, emergency service isn't an issue since only long-distance calls are going over the VoIP service. All emergency calls will still use your existing PSTN circuits.

Finally, again, you get what you pay for. In my experience, the VoIP service providers' calls sound just a little better than cell phones. YMMV (your mileage may vary). But there are a few ways to work around less-than-optimal sound quality:

  • Optionally configure access codes (such as "9" to get to the PSTN or "8" to get to the VoIP long-distance service) to allow employees to select which service they want to use. Thus, they can choose to have important calls (VIPs or customers) use the PSTN.
  • If you currently block some employees from making long-distance or international calls because of the cost, you could configure your PBX to permit this group to only use the VoIP service. Moderate quality would be better for them than no service at all.

Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.

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