SRST: Re-routing autoattendant

[David Wolgast]

I have set up a branch site using IOS Telephony Service for SRST (rather then call-manager-fallback) on an H.323 gateway. The branch has an automated attendant on Unity Connection at a central site which is reached via a CUCM CTI RP with CFA to UCxn.

In the event of a SRST activation, I would like all automated attendant calls to go to the receptionist's DN, but I can't figure out how to redirect the main number to her phone. I see that call-manager-fallback has the alias command. Is there something similar in telephony-service?

[William Bell · Accepted solution]

There are two options I can think of:

1. CFA on ephone-dn

With this option you configure a static ephone-dn on your h233 gateway and a corresponding dial-peer. Let's say your main line number is 4000 and your receptionist DN is 2000. The following config (in addition to other CME configs) should do the trick.

ephone-dn 10

number 4000

call-forward all 2000

pref 2

!

dial-peer voice 4000 voip

destination-p 4000$

pref 1

session target ipv4:x.x.x.x

dtmf-r h245-alpha

no vad

voice-class h323 x

voice-class codec x

!

I am only showing one voip dial-peer, you may need more. The point is we created a dummy ephone-dn that is call forwarding unconditionally to the operator line. We only want this to be present in CME-SRST mode. If you were using a MGCP gateway then we could just go with the ephone-dn config. Since you have a h323 gateway, we need to avoid a situation where we are hitting the ephone-dn on all calls. So, we add specific voip dial-peers for the same DN but with a lower preference value (lower == more preferred).

During normal ops you hit the voip dial-peers. During CME-SRST mode, you still hit the voip dial-peers but your router will fail to establish a TCP socket with CUCM and will "hunt" to the next dial-peer (note, ephones are just logical reps of a POTS dial-peer - use "show telephony-s dial-peer" to see what I mean).

For this to be usable, you would want a h323 voice class that specifies a pretty shor h225 tcp establish timer. I would go with 2 or 3 (tops).

2. BACD with Drop Through

BACD (basic ACD) is TCL application (set of apps, actually) that you can run on an IOS router. CME-SRST mode is a good candidate for this solution. BACD is basic but discussing ALL of the options here would be way too heavy for the question. There are good examples on CCO

http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/bacd/configuration/guide/cme40tcl.html).

With Drop Through, you can use a dial-peer to launch the BACD service. The service can "drop through" to the other DN (operator). This approach is intended for use with hunt groups and basic queueing services. Doesn't sound like it would apply to your environment (at least based on what you have shared).

You still have to contend with the dial-peers and preference options. So, the trade-off is the same. The upside is you can have queueing for more than one operator line/huntgroup.

Option 1 is cleaner based on what you relayed.

HTH.

-Bill (http://ucguerrilla.com)

[David Wolgast]

Thank you so much!

So on the lower-preference dial-peer for SRST, should the session-target bet the local gw address or does SRST take care of that? I already have Pref 1, 2, & 3 dialpeers for the DN set up toward CUCM.

[William Bell]

The dial-peers associated with ephone-dns are not voip dial-peers. They are POTS dial-peers. I know it sounds funky but that is how it works. So, you don't specify a session target for the ephone. You can bump the preference up on the ephone-dn to something >3 and <=10.

-Bill (http://ucguerrilla.com)