Why can't I write more than 8 numbers or letters in serial number?

[moodnasser]

I cannot complete it because the serial number is forced to contain 8 letters or numbers
Is there a way to write more than that?

[pmiron]

I guess your problem is to replace an Huawei ONT.
The point is you should replace the first 4 hexadecimal digits to ASCI.
For isntance: 4857544361DE3C1A (48 57 54 43) -> (H W T C or HWTC(stands for Huawei))
So 4857544361DE3C1A will become HWTC61DE3C1A.
HWTC + 8 digits (61DE3C1A)

[moodnasser]

thanks

I have a question . What is it --slid The SLID (or PLOAM Password).
Is it the password for the service provider's modem?