Trusted Phone Number List

I have a GX450 with ALEOS 4.9.3 and on the menu tab Services then SMS, I am trying to add a Trusted Phone Number list number that is only 6 digits long, but it gives me an error of Must be length of 7-15 digits long. Why do we have this restriction since providers send messages with only 3 digits long and some big operators. Yes I agree under normal usage the number will between 7-15 fine. Maybe give a message saying your number is not between 7-15 are you sure you want this? Yes/no. In the mean time I have to have Trusted Phone Number disabled for things to work, but I can spam SMS’s that I have to deal with. Is there any way to put it in bypassing the menu? I cannot request the provider to put in a password to allow it to go through either.