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UC520 Teleworker

Arthur Kant
Level 1
Level 1

I have a UC520 with two teleworkers in different sites.  All sites connect back to UC520.  Calls between phones and the "Hub" work well but calling between each other is not working.  These are true L2L ipsec tunnels with no mesh.  Do I need to have ip connetivity directly between phones in order for them to work?  I had always thought as long as phone could hit CME the magical world of call delivery would work.

21 Replies 21

David Trad
VIP Alumni
VIP Alumni

Hi Arthur,

This might be a silly questions but do you have transcoding in place?

Are you forcing any particular codec on the teleworker phones on the CME side?

Cheers,

David.

Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *

Not a silly question :)  there is no transcoding configured on the system, all G711 to make things simple.  I have this problem now with two clients.  One using traditional CME on ISR and the other with UC500.  Both deployments are setup with a hub and spoke topology.  Static site-to-site (non EZVPN) tunnels back to the head end.  Teleworkers can call great to main office phones.  But the problem is teleworker to teleworker.  Teleworker tunnels are setup to just encrypt data to head end and not between sites (like a DMVPN ..etc / Mesh) so I am thinking this has something to do with it.

I wonder if its ACLs on eack teleworker router to allow the subnet of the other?

When you set up a teleworked with CCA, it takes care of TW Router and UC500, but it doesnt know about the others, maybe?  Not sure.  Thinking out loud I guess...

I can confirm that they do not have acl's for the other "spoke" subnet.  So the big question is: On a CME system must all individual SCCP phones have IP access each other in order to make successful calls or can you hairpin RTP ..etc for voice through the router.

Your right.  I was confused with data VLAN for a moment.   A registered phone on the host UC500 should be enough for call control.

What happens when the two remote Teleworkers attempt to call each other. By default RTP traffic is directly between the phones and control traffic is through the central unit. You can configure hairpin in CME but I would assume that would be your issue if the two phones can call each other (ringing) but are unable to connect the audio.

That makes sense to me what is happening is in this scenario is the user can call the other phone and make it ring just fine.  However this is no sound at all through the channel.

However on our other system we have a lot of teleworkers, configured the same and there is really no problem between teleworkers except for one single user.  Everyone else is just fine and we have the same tunnel configuration where we are only encrypting for the head end office subnet.

What would be the command to allow for hairpinning media through cme?  Something under ephone  ?

Ok this issue has been resolved.  The problem was that I did not have the "mtp" command under the ephone's in question.  Without this command in place the phones will attempt to RTP directly between phones.  If this command is enabled it forces RTP through the CME router.  Thank you all for the brainstorming to figure this out.

Kenny

That makes sense, make the media terminate in CME. Glad you got it figured out.

Kenny,

Did you configure with CCA? If so, I want to nake sure we address why that didnt get configured.

Steve

Steve CCA appears to remove the mtp command on the ephones.  I have to always put the command back in.

Thanks Kenny, I will look into this.

Steve DiStefano

Technical Solutions Architect

Small Business Sales

Cisco Systems Inc.

Research Triangle Park

North Carolina, U.S.A

1.919.392.6219

www.cisco.com/smb

What version of CCA do use?

Steve

Most recently I used the new 2.2(4) -  We had UC520 where we configured the "mtp" com

mand manually under each ephone.  We then (using 2.2(4)) Upgraded the box to 8.0.2 .  Once the upgraded was complete did some configuration of new phones using CCA 2.2(4) .  The next day users told me the problem had came back.  I checked the ephones (these were existing ephones not the new ones we added) and they did not have the mtp command.  I put the command back in and resolved the issue.

Kenny

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