Why is the message I send split into two messages?

This happens due to concatenation.
A standard message can contain 160 characters. Messages containing more characters will be split up. The length of the split messages will contain max 153 characters.
A Unicode message can contain 70 characters. The length of the split Unicode message will contain max 67 characters.
NOTE: Not all destinations accept/allow concatenation!

See also: https://en.wikipedia.org/wiki/Concatenated_SMS

Sending an SMS

• What happens when the recipient's phone is off or on divert?
• Can I view my history?
• Is it possible to have a personalized senderid?
• Do you provide delivery reports?
• Why is the message I send split into two messages?
• What can I use as a senderid?
• How do I change my senderid?
• Can I receive replies to the messages I send?
• Is there a maximum to the amount of messages I can send?
• How many characters can an SMS consist of?
• What are the costs?