My first guess is that you aren't actually hitting the translation pattern you created. No you don't necessarily need to create a new partition, but as always, it depends on your setup. For simplicity I would keep the translation pattern in the same partition as the Directory Number (DN) that you are using now.
The main question is where does this hotline number ring to today? Does it hit a CTI route point, does it ring to a DN on a phone, does it hit a Hunt Pilot, etc. Whatever this number is, that is the DN/number and partition where you need to create your Translation Pattern in. For good measure, I personally always change the "Called Party Transform Mask" to a new location so I KNOW that the translation pattern is being hit, b/c it will then be redirected to a new DN. Then, just change where your call ends up today to this new target location.
For example:
Say your hotline number is 5551212 and you are only looking at the last four digits today, so you have a four digit numbering plan, in this case the end Hunt Pilot is x1212.
Create a new translation pattern for 1212 in your regular DN partition and st the Calling Search Space to whatever your phones use. This translation pattern will change the "Calling Party Transform Mask" to 0000000000 to hide the original caller's number. It will also change the "Called Party Transform Mask" to a new location. This can be your desk phone's DN for testing purposes, or it can be the hunt pilot number. Of course it cannot be the existing pilot of 1212 b/c then you would have two "devices" in the same partition with the same DN which isn't allowed. So change the translation pattern's "Called Party Transform Mask" to point to a new DN, say 7777 and change the Hunt Pilot to 7777 as well (from 1212). This way you KNOW incoming calls are hitting your newly created translation pattern b/c they are landing on your new Hunt Pilot of 7777.
