Cisco SPA-122

The Cisco SPA122 is one of Cisco’s most widely deployed ATAs. It has two FXS ports and a single 100BaseT WAN network interface (no router).


1. Firmware

Update to the latest firmware for the Cisco SPA122 before connecting to our service. You can download the current production release from the link above. Once downloaded, you'll navigate to "Administration -> Firmware Upgrade" and click the "Browse" button. Select the file you downloaded from Cisco's website, and then click "Upgrade" once this has completed your device will reboot. You can then move on to the steps below.


2. NAT Settings

Click "Voice" in the primary navigation bar, and then select either Line 1 or Line 2 depending on your circumstances. In our example we use Line 1. Configure the following options under the "NAT Settings" menu:

Configuration Option Required Value
NAT Keep Alive Enable : Yes


3. SIP Settings

Under the "SIP Settings" section, make the following change:

Configuration Option Required Value
SIP Port : 5080 help


4. SIP Registration

Under "Proxy & Registration" and "Subscriber Information" configure the following options:

Configuration Option Required Value
SIP Port : sip.t38fax.com:5080 help
SIP Port : SIP Username help
SIP Port : SIP Password help


5. Additional Settings

In the "Supplementary Service Subscription" and "Audio Configuration" sections, enter the following options:

Configuration Option Required Value
Call Waiting Serv : No
Three Way Call Serv : No
Preferred Codec : G.711u (USA) or G.711a (rest of the world)
Use pref. Codec Only : Yes
Silence Supp Enable : No
Echo Canc Enable : No
FAX Passthru Method : REINVITE
FAX Enable T38 : Yes
FAX T38 ECM Enable : Yes
Fax Tone Detect Mode : Callee Only


6. Line 2

If you do not plan to use Line 2 of your ATA, skip this section entirely and proceed to the next step (Fax Machine) to configure attached fax machine(s).

It is possible to use the SPA122’s second line with T38Fax, in either of the following two ways:

1. Second Fax Machine with the same SIP credentials, and a second fax number (one single Power-T.38 account).

This scenario is the most popular, and enables your SPA122 to service two separate fax machines, with two separate fax numbers independently. Incoming faxes are delivered to each respective fax machine directly, and on the outbound side each machine appears to be its own separate entity complete with an independent Caller-ID.

First, return to the "Voice -> Line 1" section, and locate the "SIP Settings" section. Make the following changes:

Configuration Option Required Value
Restrict Source IP : Yes

Now scroll to the "Proxy & Registration" section, and make the following changes:

Configuration Option Required Value
Make Call Without Reg : Yes
Ans Call Without Reg : Yes

Next, navigate to the "Voice -> Line 2" section, and locate the "SIP Settings" section. Make the following changes:

Configuration Option Required Value
SIP Port : 5080
Restrict Source IP : Yes

Now scroll to the "Proxy & Registration" section, and make the following changes:

Configuration Option Required Value
Make Call Without Reg : Yes
Ans Call Without Reg : Yes
Register : No

Finally, scroll down to the "Subscriber Information" section, and make the following changes:

Configuration Option Required Value
User ID : DID-Alias (The Second DID assigned to this trunk.)
Password : SIP Password (Same as Line 1)
Auth ID : SIP Username (Original/Line 1 Username)
Use AuthID : Yes
SIP URI: : sip:DID-Alias@127.0.0.1:5080 error(Be sure to replace DID-Alias with your 2nd number.)

See the screenshot below for a better understanding, in our example 18043027006 is our SIP Username, and 18043027009 is an additional DID on that account.

2. Second fax machine with different SIP credentials (two separate Power-T.38 accounts)

This scenario is most often used when the two fax machines must receive faxes independently from one another, for instance if one fax machine is for your sales team, the other one for accounting, and the two must never mix. In this case you would have two separate username/password combinations, and you would configure line 2 exactly as you configured line 1, with the following changes:

Next, navigate to the "Voice -> Line 2" section, and locate the "SIP Settings" section. Make the following changes:

Configuration Option Required Value
SIP Port : 5081


7. Configure your Fax Machine

Finally, configure your fax machine to work properly with your Power-T.38 SIP Trunk. Review the following guide for details:

Recommended Fax Machine Settings

Why 5080? Learn More

Enter your SIP Username here. (This should be a DID assigned to your account that is available for registration. IE: 18043027000)
Still Confused? Learn More!

Enter the SIP Password for the SIP Username you entered above.
Still Confused? Learn More!