This is the second post in the two post series. It will go into more detail on the configuration of the solutions and workarounds put in place.
- The Communications Manager Express (WebEx local gateway / CUBE) requires a security license. There's not much else to add. Make sure it has one so the CUBE will accept the TLS commands.
- The CME phone directory numbers will by default register to the WebEx Control Hub. According to TAC this can confuse the Webex Control Hub and cause issues. The symptom of the phones trying to register with Webex is evident with a “show sip-ua register status”. It will show the directory numbers of all the CME phones trying to register to Webex. TAC explained that it should only show the SIP trunk trying to register to Webex. (It’s also normal to see registration for a SIP IP Telephony Service Provider too if it's configured for authentication) TAC offered a configuration sample to prevent the SIP devices from registering with Webex and I looked up how to prevent the SCCP devices and POTS device ports. Please see the following three configuration samples.
- SIP phones on the CME will need their directory numbers configured as “no-reg”
voice register dn <>
no-reg
- SCCP phones on CME will need their directory numbers configured for “no-reg”
- Analog phones connected to CME will need to have their pots dial-peer configured not to “sip-register” it's destination-pattern
dial-peer voice <>
pots
destination-pattern <>
port <>/<>/<>
no sip-register
Note: In my case, I had to reboot the CUBE before the configuration changes took full effect.
ExampleCME#show sip-ua register status
Tenant: 10
--------------------- Registrar-Index 1 ---------------------
Line peer expires(sec) reg survival P-Associ-URI
================================ ========= ============ === ======== ============
5555551212 -1 239 yes normal
Tenant: 200
--------------------- Registrar-Index 1 ---------------------
Line peer expires(sec) reg survival P-Associ-URI
================================ ========= ============ === ======== ============
ExampleCME.Trunk1234_LGU -1 39 yes normal
ExampleCME#
- The CME location in the WebEx Control Hub needs to have the main phone number associated with it. This is kind of an interesting step because the CME is not hosting Webex Calling phones but rather it's hosting its own CME phones. However, Webex won’t pass calls without the main phone number configured. I chose an unused DID the customer owns, added it to the control hub, and associated it to the location the trunk is tied to.
- The CME dial-peers directed at the WebEx cloud didn't present the SIP signaling in a way that the WebEx cloud expected to see it. According to Cisco TAC their configuration guide was designed for the CUBE to front end a Communications Manager or other PBX device. Cisco TAC suggested hair-pinning the dial peers to obfuscate CME from WebEx Calling. TAC also helped me do a little bit of dial-plan manipulation prefixing digits so that the CUBE didn't drop the calls as a "loop". Technically TAC said CME isn't explicitly listed as being supported however, this workaround presented the SIP signaling to the Webex cloud in the Webex expects to see it. Please see the following information on how the dial-peers and translations were configured:
Inbound calls from WxC to CME
The "Configure Local Gateway
on IOS-XE for Webex Calling" guide from Cisco includes dial-peers without
any dial-plan numbers tied to them. In their example, they show dial-peer
200201 matching inbound calls from Webex Calling and then sending it along to
dial-peer group 300.
Example of a portion of the reference configuration in the "Configure Local Gateway on IOS-XE for Webex Calling" guide from Cisco:
dial-peer voice 200201 voip
description Inbound/Outbound Webex Calling
destination dpg 300
I took Cisco’s example config and modified the dial-peer group so that it passed the calls to my dial-peer 444001 below. This dial-peer hairpins the calls back onto the CME and prefixes a 444 so the CUBE doesn't drop the call as a duplicate.
dial-peer voice 4440001 voip
description Inbound calls from WxC to CME -
Prefix 444 and loop via CUBE
translation-profile outgoing add444
destination-pattern 8040..$
session protocol sipv2
session target ipv4: <CME IP Address>
voice-class sip early-offer forced
voice-class sip bind control source-interface
Loopback0
voice-class sip bind media source-interface
Loopback0
dtmf-relay rtp-nte sip-kpml sip-notify
codec g711ulaw
no vad
This inbound dial-peer matches the call with the 444 prefix and strips it off. Then the CME phone will match the outbound leg.
dial-peer voice 4440002 voip
description Inbound calls from WxC
to CME - Strip 777 Webex Calling Strip 777 - WxC Side
translation-profile incoming strip444
session protocol sipv2
session target sip-server
incoming called-number 444T
voice-class sip early-offer forced
voice-class sip bind control source-interface
Loopback0
voice-class sip bind media source-interface
Loopback0
dtmf-relay rtp-nte sip-kpml sip-notify
codec g711ulaw
no vad
Outbound Calls from CME to WxC
This outbound dial-peer matches the
directory number of phones on WxC, then prefixes a 777, and then loops the call
back through the CUBE.
dial-peer voice 7770001 voip
description Outbound calls to WxC
- Prefix 777 and loop via CUBE
translation-profile outgoing
add777
destination-pattern 8070..$
session protocol sipv2
session target ipv4:<CME IP Address>
voice-class sip early-offer
forced
voice-class sip bind control
source-interface Loopback0
voice-class sip bind media source-interface Loopback0
dtmf-relay rtp-nte sip-kpml sip-notify
codec g711ulaw
no vad
This dial-peer matches the inbound call leg for calls routed to the 777 prefix.
dial-peer voice 7770002 voip
session protocol sipv2
session target sip-server
incoming called-number 777T
voice-class sip early-offer forced
voice-class sip bind control source-interface
Loopback0
voice-class sip bind media source-interface
Loopback0
dtmf-relay rtp-nte sip-kpml sip-notify
codec g711ulaw
no vad
This dial-peer matches the outbound
call leg for calls with the 777 prefix. Strips off the prefix and the routes
the call out to Webex Calling
dial-peer voice 7770003 voip
description Outbound calls to Webex Calling
Strip 777 - WxC Side
translation-profile outgoing strip777
max-conn 150
destination-pattern 7778070..$
session protocol sipv2
session target sip-server
destination dpg 300
voice-class codec 99
voice-class stun-usage 200
no voice-class sip localhost
voice-class sip tenant 2000
dtmf-relay rtp-nte
srtp
no vad
The information below shows the translations config:
voice translation-rule 4441
rule 1 /\(......\)/ /444\1/
voice translation-rule 4442
rule 1 /^444\(......$\)/ /\1/
voice translation-rule 7771
rule 1 /\(......\)/ /777\1/
voice translation-rule 7772
rule 1 /^777\(......$\)/ /\1/
voice translation-profile add444
translate called 4441
voice translation-profile strip444
translate called 4442
voice translation-profile add777
translate called 7771
voice translation-profile strip777
translate called 7772
