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Save Money On Common Area Phones with Microsoft Teams Direct Routing

Now that Direct Routing has been released on General Availability worldwide for Microsoft Teams it is a very exciting time for Microsoft Cloud UC. Aside from the obvious benefits of Direct Routing such as migration path, investment stretching and interop with other systems, it does offer some interesting alternatives to Microsoft’s cloud native offering for those that perhaps have budget constraints.

When evaluating cloud licensing offerings for different use cases, one thing that stood out was the Common Area Phone license. It’s £6 per device plus a calling plan. Add this to the cost of a Skype for Business Online certified phone the cost per unit would be quite high for a device that wouldn’t be used that often. The most common Skype common area phone is the Polycom VVX 301 at £100-£120 per unit, add that to the licence cost £6 for the CAP SKU and £9 for the simplest calling plan licence and you have a monthly commitment of £15 per month or £180 per year. Now multiply that by a few hundred that you may have in your business, you realise that this is quite a substantial investment.

If your deploying Direct Routing then you have an alternative option.

Most SBCs that you’ll buy will come with the ability for local SIP registration subject to a nominal licence fee. You can use this feature for your common area phones. Instead of creating a common area phone account in Office 365 and consuming a licence, create a SIP account on the SBC for the device instead. This allows the phone to register directly to the SBC instead of Microsoft Phone System. The benefits of this mean that you now open yourself to the market of standardised SIP devices such as the SNOM D120 which is about £50 per device as you do not need certified Skype for Business or Teams devices for this.

There are some draw backs of course:

  • Not being able to search the address book
  • Not being able to see a user’s presence
  • No HA or DR – SIP registration is to a single SBC only without failover

But when you look at the usage of a common area phone, in most cases, the person that is using it already knows the number they wish to dial. However, you can use Microsoft Phone System features to provide a directory service to these common area phones

Create an Organizational Auto Attendant in Office 365 that is configured to search the company directory by name and use voice recognition. Create a transformation rule on the SBC to transform a speed dial into the OrgAA phone number and route that through your existing Direct Routing SIP trunk to Microsoft. Then when a user needs to find someone, they can dial the speed dial from the common area phone, speak the name of the person they want to contact and the OrgAA will search the GAL and connect you to that person. No need to remember their number and it often takes the same amount of time, or less to do this than using the dialpad to search the GAL from a SfB phone.

Normal PSTN calls can be routed out of the SBC as normal.

But what if a Microsoft Teams user needs to dial a common area phone? Sometimes this is necessary depending on what you are using the CAP for. So, in order for them to be able to search the GAL for the CAP account you create a contact object in your AD and sync it to Office 365 with the phone number of the CAP. Then create a voice routing policy that routes calls to the SBC over the Direct SIP Trunk.

This solution means that you do not need to purchase the Common Area Phone Office 365 licence or a calling plan.


    • yes, you’d need a route to the LAN the SBC is on even public IP will be fine with correct settings

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