Don’t double-count extended GSM characters if text message is not GSM encoded #1371
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Characters like `{` only count as two characters if the message is
GSM-encoded.
If characters like Ŵ have caused the message to not be GSM-encoded then
`{` counts as 1 character like any other.
This bug existed before https://github.com/alphagov/notifications-utils/pull/1362/files
but wasn’t spotted. It’s quite unlikely to make a real-life difference
to billing given how infrequently these characters are used in messages.
Only 2 is the special case because that’s where the previous fragment varies in length. The maths in the general case works for 1-fragment messages
quis
changed the title
joybytes
approved these changes
Jun 15, 2026
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Characters like
{only count as 2 characters if the message is GSM-encoded.If characters like
Ŵhave caused the message to be unicode-encoded then{counts as 1 character like any other.This bug existed before #1362 but wasn’t spotted. It’s quite unlikely to make a real-life difference to billing given how infrequently these characters are used in messages.