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New Member

VoIP design

Hi all,

i have to install ( for a small office ) 15 IP phone with a Call manager espress but i have few few question for you:

1) Best practise suggest to have one Vlan for IP Phone and one for PC: isn't it ?

2) Where is the best Vlan to place CM Express ? ( Voip Vlan or PC Vlan ? )

3) If i have one Layer3 switch ( with the 2 vlan configured ) and the access wan router also connected to it what is the best practise for IP phone default gateway ( router or Layer3 ) ?

Thanks in advance for your help



Re: VoIP design

1 - Yes

2 - I would put CME router in voice vlan. But if the same router is being used for data and voice, then it really is not a big gain to put the router in one vlan over the other.

3 - If L3 switch has 2 SVI (vlan interfaces) configured, then you can set the L3 switch as the default gateway. On the L3 switch, you can run a default route to the WAN router as next hop. The CME can remain in the voice vlan.



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Re: VoIP design

#1 yes

#2 voip

#3 L3 Switch can be the DG for the pc/phones with default route pointing to the wan router.

U can do the following:

1. keep it simple with 2 vlans as originally plan

or if you want to be more granular

2. can add a 3rd vlan for the management vlan

3. if you have a firewall, add a 4th vlan for it.

New Member

Re: VoIP design

Thanks you for you reply,

another question:

If i have also a VG224, i have to place it also in VoIP vlan near to CME ?

Thanks again


New Member

Re: VoIP design

That would be correct.

Re: VoIP design


That would sound logical to add VG224 to the same vlan.


Hall of Fame Super Silver

Re: VoIP design

Make sure however to configure the switchport where the vg224 is connected with "switchport access vlan ", and do not add "switchport voice vlan <>" command. The GW unlike the phones does not recognize the voice vlan so this way you can assign it to voice VLAN.


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