Voice Gateway Router to Analogue Connection - FXO or FXS

[michaelgitonga]

Hi,

I have the following scenario:

• Central Cisco Call Manager serving branch IP Telephones
• Each branch has
  • Cisco IP Phones
  • Cisco WAN router
  • Existing Analogue PBX and Analogue Phones

I would like to have the analogue phones call the Cisco IP Phones. The question is:

1. Which port type do I use in the Cisco WAN router to connect to the Analogue PBX? Is it FXO or FXS
2. Do I connect to the Analogue PBX's FXS port OR Trunk port?

[Slavik Bialik · Accepted solution]

Do you have the ability to connect a E1/T1 to this analog PBX?

If so, you'll need a T1/E1 card in your WAN router, for example: VWIC3-1MFT-T1/E1.

Can you show us the output of "show inventory" from your WAN router?

[michaelgitonga]

Hi Slavik,

This is a design scenario. Assume the Analogue PBXs do not have E1 ports and have only

1. Trunk Ports for connecting to Telco
2. FXS ports for connecting analogue Phones

Kindly advice on the following:

• On the Analogue PBX, to which port does the router connect to: Trunk port or FXS port?
• On the router, do I use FXO or FXS port to connect to the analogue PBX?

[Slavik Bialik · Accepted solution]

Hi Michael,
You need to connect it to FXO.
You can get some FXO gateway, or a module to a router (never had experience with FXO modules in Cisco, so I'm not familiar with SKUs of those modules), and just configure a SIP trunk from CUCM to this gateway and on the other side you'll connect FXO ports to your analog PBX.

[michaelgitonga]

Slavik,

Thank you.

[Rajan · Accepted solution]

I guess the below discussion would help:

https://supportforums.cisco.com/t5/ip-telephony/fxs-vs-fxo/td-p/743539

On the router we usually connect the line from PBX to FXO port. But the condition here is FXS side always need to provide ring, voltage, and dial tone to the FXO side.

HTH
Rajan
Pls rate all helpful posts

[michaelgitonga]

Rajan,

Thank you.