Odd problem with AAH and GXP-2000 with *70

I am using AAH with 4 Grandstream GXP-2000 IP Phones.
When I dial any of the following numbers the phone hangs up and gives me a dialtone:
*72, *73, *90, *91.
It seems to be numbers that handle incoming calls (forwarding and call waiting etc).
If I change the numbers in the conf file to *42 *43 etc it works, also this problem does not happen from a softphone (x-lite) so it seems to be the Grandstream phones.
Anyone got any ideas what could be wrong?

Thanks in advance

the phones own vertical service codes probably. download a manual and you’ll probably find that those codes are used by the phone to configure it’s own forwarding, DND etc.

i’m not sure you can turn them off on the GXP either, you’ll need to re-write bits of your config files to change them.

Yea you are right the numbers are reserved for the phone, luckely they can be disabled in the GUI.