Well, if you are looking to forward unconditionally, as Stephanie said, your phone should already have a setting for this that you can preset and toggle on and off, so it is available for you to do quickly, without adding it to your address book. Conditional codes and different destination numbers might be very useful to add to your address book, however.
Sorry i did not add the "Unconditional" Call Forward
We prefer customers do it throught their phone for many reasons.
Mainily because customer tend to forget GSM codes.
Also depending if you have Vociemail or not there may be diffrences to the answer we provide.
Glad I helped
It is possible to change the CF settings on an account but you may have to cancel existing VM subscription. Also, once this is done and you call your mobile phone and the call diverts, Fido does not populate the RedirectingPartyID (Call diversion header in SIP) so if the call is diverted to a Customer Premise Equipment (CPE) then the subscriber ID is not known. See SIP trace attached (you need to download wireshark (free) to view)
Hence my use of the word 'maybe'.
And your original question was simply 'how' without the further qualification of looking specifically for the GSM codes. So, while her answer didn't provide GSM codes, she did ask for the model so she could provide the instructions for the settings of the device. As to why she didn't follow up afterwards, well you asked for the codes yesterday at almost 6PM Montreal time, so maybe she was gone for the day and by time she got back into the thread today she saw JasonB had already answered the question.