remote ip phone with cme on the main

Unanswered Question
Feb 9th, 2008

hello,

is it possible to have an ip phone on the remote thru the wan if iam having call manager express on the head office..

thanks

I have this problem too.
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Paolo Bevilacqua Sun, 02/10/2008 - 03:12

Yes, it's absolutely possible.

You can use either g729 or default g711 codec, depending on you wan situation.

Hope this helps! Please rate post if it does!

Paolo Bevilacqua Sun, 02/10/2008 - 04:12

Yes, sccp works over tcp and is routable just like any other ip packet.

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Paolo Bevilacqua Sun, 02/10/2008 - 09:51

Really no special config is needed. If you don't have IP connectivity between the remote phone and the voice vlan, under ephone configure 'mtp". If you want codec g729, do configure that.

Nothing else is required.

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pcameron Tue, 02/12/2008 - 13:56

Here is a working config fro a remote phone registering on a local CME and using G729.

You will need an IOS that runs CME version 4.1 to use the G729 option under the ephone. You also need to set up transcoding to allow the remote phone to interwork with the local devices which will be using G711.

MAC addresses and IP addresses will obviously have to be altered.

!

sccp local GigabitEthernet0/0

sccp ccm 172.19.150.56 identifier 1

sccp

!

sccp ccm group 1

associate ccm 1 priority 1

associate profile 1 register MTP0013c49a0cd0

keepalive retries 5

!

dspfarm profile 1 transcode

codec g711ulaw

codec g711alaw

codec g729ar8

codec g729abr8

codec gsmfr

codec g729r8

maximum sessions 90

associate application SCCP

no shutdown

!

telephony-service

load 7960-7940 P00307020300

max-ephones 100

max-dn 300

ip source-address 172.19.150.56 port 2000

system message Test System CCME 4.1

sdspfarm units 1

sdspfarm transcode sessions 128

sdspfarm tag 1 MTP0013c49a0cd0

voicemail 7800

max-conferences 24 gain -6

call-forward pattern .T

moh music-on-hold.au

multicast moh 239.1.1.1 port 2000

web admin system name admin password cisco

transfer-system full-consult

transfer-pattern .T

secondary-dialtone 9

create cnf-files version-stamp Jan 01 2002 00:00:00

!

!

!

ephone-dn 2

number 6002

call-forward busy 7800

call-forward noan 7800 timeout 10

!

!

!

ephone-dn 5 dual-line

number 6005

call-forward busy 7800

call-forward noan 7800 timeout 10

!

!

ephone 5

device-security-mode none

username "Dweezil"

mac-address 0011.5C0E.571B

paging-dn 99 unicast

! Paging should be set to unicast if multicast-routing is not enabled on WAN:

codec g729r8 dspfarm-assist

mtp

type 7970

button 1:5 2:2

cfajardo1_2 Fri, 02/22/2008 - 00:18

i just found the document that relates with this issue. the doc is from the

IPTX ver4. vol 1

Cisco Training and Certification notes which states;

"Registrayion accross the wan is not supported. The ip phones must be on the local LAN with the cisco unified call manager express router'

cfajardo1_2 Fri, 02/22/2008 - 03:36

sorry forgot to put the page numbers

IPTX ver4. vol 1

page 1-9

Cisco Training and Certification

cfajardo1_2 Fri, 02/22/2008 - 05:10

on one part of the link it says the following but isnt it that cme DOESNT support CAC?

----------------------------------------

SCCP: Enabling a Remote Phone

To enable IP phones or instances of Cisco IP Communicator to connect to a Cisco Unified CME system over a WAN, perform the following steps.

Prerequisites

•The WAN link supporting remote teleworker phones should be configured with a Call Admission Control (CAC) or Resource Reservation Protocol (RSVP) solution to prevent the oversubscription of bandwidth, which can degrade the quality of all voice calls.

pcameron Fri, 02/22/2008 - 06:19

CME has no concept of a remote region. Even though you can register phones remotely using the configs I posted earlier, it still assumes all phones are local and it has no awareness of any form of call admission control (CAC). So if you have bandwidth limitations, CME won't perform any form of bandwidth reservation or alternate rerouting. The best suggestion here would be to set up a LLQ class that gives absolute priority for the sccp and rtp traffic, and ensure that there is no chance of the link being oversubscribed by too many remote devices.

cfajardo1_2 Mon, 02/25/2008 - 21:59

but in this case we cannot control the max number of calls traversing the wan

Paolo Bevilacqua Tue, 02/26/2008 - 13:33

I think the documentation part about cac and rsvp is misleading, and Paul's advice is correct.

However to limit calls for a remote cme phone is easy, as you control the number of lines you give to it.

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