Hi Rafael,
For the ATA running SCCP and FXS running SCCP (Supplementary services) Call Forward All is **1 then the number Call Forward All Cancel is **2;
Activate Call-Forward-All
Use this feature to send all calls from one telephone number to another telephone number. To activate Call-Forward-All, follow these steps:
Procedure
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Step 1 Press ** then 1 on your telephone keypad. You will receive a confirmation tone.
Step 2 Enter the telephone number to which you want to send the calls. A confirmation tone will sound.
Step 3 Hang up.
From this good SCCP doc;
http://www.cisco.com/en/US/docs/voice_ip_comm/cata/186_188/2_15_ms/english/administration/guide/sccp/user.html#wp1014659
For FXS;
http://www.cisco.com/en/US/docs/ios/12_4t/12_4t2/ht1vg224.html
Hope this helps!
Rob