Sms length and price - nxtele/http-api-document-en GitHub Wiki

For sms content only contains GSM7 characters

160 chars per charging unit; calculate after adding signature into content (if more than 160 chars, charging per 154 chars)

GSM7 basic characters, each char counts as 1; GSM7 extension characters, each char counts as 2.

For sms content contains non-GSM7 characters (Chinese, Japanese, ...)

70 chars per charging unit

More

GSM-7 is a character encoding standard which packs the most commonly used letters and symbols in many languages into 7 bits each for usage on GSM networks. As SMS messages are transmitted 140 8-bit octets at a time, GSM-7 encoded SMS messages can carry up to 160 characters.

GSM 03.38 Standard

GSM support chars as below Gsm7 chars

More to notice

Malaysia(Country code 60), mobile operators require the content header RM 0.00 is added to every message sent to Malaysia. This header tells the receiving subscriber that they were not charged for receiving the SMS message. Sending your messages without this header will result in the content being truncated or the message failing entirely. Concatenated messages are supported by all mobile operators except Digi Malaysia which delivers them as multiple separate messages.