What's your input character set? Latin-X? UTF-Y?
The demo section of GSM::Nbit provides a good hint: 

use Encode qw/encode decode/;
...
# We need to encode it first - for details see:
# http://www.dreamfabric.com/sms/default_alphabet.html
my $txt0338 = encode("gsm0338", $txt); # <--- look!
...

[download]
I havn't checked it, but Encode seems to have solved your problem already or can do most of the heavy lifting for you? See also: Encode::GSM0338
The link to dreamfabric seems no longer availabe, but the Wayback Machine still remembers.

In reply to Re: How to replace all non GSM 7-bit default characters? by Perlbotics
in thread How to replace all non GSM 7-bit default characters? by makafre

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