The Great Text Messaging Mystery Solved

For months I have wondered why certain text messages sent with my telephone took 2 or 3 messages (sets of credit) to send whilst other messages of the same character length only required one lot of credit. I theorised about what caused this difference.

Was it:

a) the time of the day/night I sent the messages?

b) the service provider, Telsim’s settings?

c) how soon after buying credits I made the messages (a special offer for new purchases perhaps)?

d) the mobile service provider of the message recipient (messages to other providers cost more)?

e) another random reason?

I soon discounted all but e. However, a few days ago even e was proven wrong.

The actual explanation:

A standard 2-credit message on my pre-paid Telsim account can be up to 160 characters in length. After 160 characters a second lot of 2 credits is required. However, for messages that use certain non-English characters, including the Turkish letters ı (un-dotted i) and ç, the message can only be 67 characters long before incurring a second lot of credits. If I don’t use these non-English credits I will always obtain 160 characters in value for each message. I don’t know why this is the case. I could understand if these non-English letters ‘used’ 2 or 3 character spaces per letter, but not why the single message size reduces by 93 characters!

Could any tech or telco person explain this?