There is no hard limit on the number of characters you can send within your message. However, we recommend keeping your message short to avoid using too many SMS Credits per message.
Each message credit gives you up to 160 characters. Where a message string exceeds the 160 limit, it will be split into separate packets by MessageMedia, and the last 7 characters will be used to store a unique ID that will enable the packets to be re-assembled into one message on the recipient's device. If you send a message with 200 Characters, it will incur 2 SMS Credits (e.g. 153+7 and 47+7). If you send a message with 320 Characters, it would incur 3 SMS Credits (e.g. 153+7 and 153+7 and 14+7). The number of characters being used in your message is displayed underneath the message area as shown below:
Important Note - If you include Emoji’s or Special Characters in your message, this reduces the Message Length to 70 Characters per SMS Credit, or 67 per part if the entire message exceeds 70 Characters.