Main Number Handling – Auto Attendant vs Response Group

I’ve covered Exchange Unified Messaging Auto-Attendants and Skype for Business Response Groups in some depth in previous posts, and I wanted to do a comparison between the two. The two share some overall similarities, with some major difference that will lead you to select one over the other, and minor differences that you’ll want to be aware of.

Microsoft recently released two Skype for Business Online features: Cloud PBX Call Queues and Cloud PBX Auto Attendant. These two SfBO features are roughly analogous to Exchange Auto Attendant and SfB on-premises Response Groups, however to be clear I am not referring to the Cloud PBX functions in this post unless I explicitly mention them.

Main Feature Comparison

In the following table, I state whether functionality is available in Response Group and Auto Attendant scenarios, and in some cases I provide some more clarity and detail beyond a “yes” or “no”.


Response Group

Auto Attendant

Anonymous call out

Yes, user can call as the Response Group


Management delegation

Yes, per Response Group (and associated Queues and Groups)

Not very granular, only to “Exchange UM” RBAC role within Exchange.

User lookup/dial by name (speak or spell)




Scheduled to the minute. Two open periods per day, otherwise closed.

Scheduled in 15 minute blocks, any number of blocks may be open or closed.

After-hours and holiday support



Calls delivered to

Natively to PC SfB client. Voicemail and other timeout/overflow options available.

To any SfB client, or any phone number reachable by Exchange – including PBX extensions and PSTN numbers.

Honors Team-ring, Delegation, SimRing, Call pickup, mobile clients

No, only rings the user’s PC or desk phone.



Yes, multiple choices and levels. Calls delivered to Queue, not directly to an endpoint.

9 choices, one level. Calls delivered to a number, mailbox, and can play a message

Caller can dial 0 to reach operator at anytime



Call queuing

Yes – call is delivered to a queue

No – call is transferred to the number specified

Multiple language support



Voice recognition



Text-to-speech or recorded greetings



Can read location and business hours to caller



Formal agent logon mode (user logs into and out of a queue)



Online or on-prem server based?

On-prem servers only.

(Use Cloud PBX Call Queues for online deployments)

Both. Exchange UM Auto-Attendants have the same functionality on-prem and online.

Can deliver calls to on-prem user



Can deliver calls to online user

No, users must be homed on-prem.


Can assign multiple phone numbers to reach it



Can record greetings via telephone



The details in this table refer to native functionality of the Auto Attendant or Response Group solution. For example, you can only natively assign one Line URI to a Response Group workflow. If you wanted to have multiple numbers to reach a workflow, there are a number of ways outside of Response Group functionality that would permit you to do that.

Final Considerations

An additional consideration that you’ll need to make is the topology of the Exchange and SfB environments. If a call comes in from the PSTN via an SBA in a branch office and has to traverse the WAN to a central office to Exchange and SfB servers, the two solutions are equal. If you are using Exchange Online, calls to your Auto Attendant now have to traverse the Internet to the cloud.

In the not so distant past, I worked with a client in a “PSTN into the SBA” scenario, where calls had to traverse the WAN to reach Response Groups, and the WAN and an underspec’d VPN to a privately hosted Exchange system. That VPN was spec’d for email (and the specs weren’t even generous for that) not voice, so voice, Auto Attendant, and Subscriber Access suffered accordingly.

And finally, make sure you’re supporting REFER, and that your firewalls allow appropriate media flow between all of your clients and servers involved in these scenarios. Appropriate levels of bandwidth and QoS are also a must.

Up next: Cloud PBX Auto Attendants and Call Queues, the Cloud PBX cousins of Exchange Auto Attendants and SfB on-prem Response Groups.

Cool Tool – Find duplicate LineURIs

Every once in a while – and by that, I mean ALL. THE. TIME. – I run into a situation where a number that I’ve been asked to provision as a LineURI for a SfB endpoint is already in use:


“Filter failed to return unique result” has got to be one of the most frustrating errors that you can receive. At least it doesn’t tell you to contact your system administrator…

Sometimes this is easy to figure out by searching for that number in the User Search section of the Control Panel:


And other times it’s not, because the number is hiding, assigned to one of the following:

  • User LineURI
  • User PrivateLine
  • CsAnalogDevice
  • CsCommonAreaPhone
  • CsExUmContact
  • CsDialInConferencingAccessNumber
  • CsTrustedApplicationEndpoint
  • CsRgsWorkflow
  • CsMeetingRoom LineURI
  • CsMeetingRoom PrivateLine

And you know what you don’t want to do? You don’t to have to dig out PowerShell and search all of these manually. What you need is a script to do this for you, and while there are a couple out there, the one by Lasse Wedø is my favorite.

It’s comprehensive, well-written, has nicely formatted output, and has a tonne of parameters available if you want to do a more complex search. The simplest form of search looks like this:

PS Search

which seems just about right to me. Download the script and give it a try next time you run into duplicate number issues.

Main Number Handling – Auto Attendants

I’ve written quite a bit about SfB Response Groups, so let’s dive into their Exchange cousin, the Auto Attendant – AA for short.

Auto Attendants allow Exchange to answer calls to your organization. You can play greetings, set schedules, allow callers to reach your users by saying or spelling a user’s name or dialing their extension, or you can provide them a list of options that they select by pressing a key.


To create an Auto Attendant, open the Exchange Admin Center, select UM dial plans, open the dial plan that you want the AA created under, and click the + in the Auto Attendant section.

You’ll need to provide a name, indicate if you want the Auto Attendant active immediately after you create it (you might not if you’re preparing for a future migration), indicate whether you want the AA to respond to voice commands, and provide a phone number to reach the Auto Attendant at. Note that you don’t *have* to provide a phone number, which is handy for lab work and setup before a migration. You will of course need to circle back and provide at least one phone number before anyone from the PSTN can use your AA to reach your organization.

If you’re in a SfB environment, you’ll need to run the New-CsExUmContact command to create a contact object so that your SfB environment knows about the AA endpoint. Non-SfB environments will need to follow different setup steps which I won’t cover here.


Now that your AA is created, you can double-click it to configure additional options.



Under General, you see the same options as when you created the AA, joined by a few others: setting a language, business name, and business location. Set the name and location accurately, as they can be read to a caller by the Auto Attendant. Here, you can also set a backup Auto-Attendant, that callers can be sent to when voice recognition isn’t working well.


Under Greetings, you can set business hours and after-hours greetings. You can also add an informational message, and optionally set this message so that callers cannot skip it. This is useful for things like unexpected closures dues to weather

Business Hours

Under Business Hours, you can set the timezone for the Auto Attendant, and then you can configure your business hours  as granular as 15 minute intervals. Here, you can also specify your Holidays using a start and end date, and specify a Holiday Greeting. Note that the holiday greeting is played from 12:01am to 11:59PM on the day(s) you configure. You can’t have the holiday greeting start at the close of business on the last day of work. You can use the announcement feature for this, or sneak in at the end of the day and reconfigure the holiday greeting to have started that day. Note that after the holiday greeting plays, callers are sent to the after-hours greeting and menu.

Menu Navigation (or not)

I’m going to skip menu navigation for now…

Address Book and Operator Access

Under address book and operator access, you can specify what permissions callers have to reach users, user voicemail without ringing the user, for searching the directory for users,  and for transferring to an operator. Note that “operator extension” here is the operators actual phone number, not what key you want the caller to press.

Dialing Authorization

Under dialing authorization, you can set where users can dial via “outdialing”.

Menu Navigation (for real)

This section is the meat and potatoes of the AA is configuration. There are two sections, business hours and non-business hours. The options within each section are the same:

  • You can upload a record prompt file – if you don’t, the AA will read the options for each entry using text-to-speech.
  • You can enable or disable menu navigation, but you do need to enable menu navigation for your AA to work, so go ahead and enable it.

If you click the + or pencil button, you can created or edit a menu entry. You need to configure the prompt, which will be read by the AA using text-to-speech if you haven’t uploaded a greeting.

Entry Configuration

You can pick when key you want to assign this action to. You can select 1-9 or timeout. 0 is reserved for reaching the operator at the extension programmed earlier.

Menu Navigation Entry

When the key is pressed, you can optionally play an audio file. After then you can select one additional action:

  • None
  • Transfer to an extension (This can be an internal or external number, so long as it is permitted by the dialing authorization rules you configured above)
  • Transfer to another auto-attendant (this is useful if you want different languages, or transfer someone to a different country or group, but please don’t try to build an IVR solution with multiple Auto Attendants)
  • You can leave a voice message for a user, without ringing them. This usually goes to a generic voicemail box
  • You can have the text-to-speech reach your business hours (you entered this carefully under the “general” section)
  • You can have the text-to-speech reach your business location (you entered this carefully under the “general” section)

The business hours and location that are read out are what you entered in the “general” section. If they are pronounced funny with correct spelling, you may need to spell them phonetically so that they sound proper. The text string that you enter is never seen by users, so you don’t need to worry about weird spellings.

If you don’t set a timeout option, callers will be offered the same menu again. I prefer this option, since there is no explicit keypress to repeat the menu choices.

Up next

Response Groups and Auto Attendants share some common features, but differ considerably with others. Up next,  a comparison of Auto Attendant and Response Group capabilities and functionality.