ICQ Won't Let Me SMS

ICQ Software Version
If the option to text doesn't exist within the ICQ software at all, it means the version of ICQ you have on your computer isn't current; the option to send an SMS via ICQ is standard. To update ICQ, select 'Software Update' from the 'File' drop-down menu and then wait for the update to download and install onto your computer. You must close ICQ and re-open it for the SMS capability to appear.
Incorrect Phone Number
Attempting to send a text message may result in an error message; one reason for a text message sending being unsuccessful is if you have entered an incorrect or invalid phone number. If you receive an error message, double-check the number to make sure it is correct. If it isn't, create a new SMS and type in the correct number prior to sending.
Phone Off
Just because someone doesn't immediately respond to a message you send via ICQ doesn't mean that sending the SMS text message has failed. One reason he might not respond immediately is if his cellphone is off, which prevents him from receiving the message. He sees the message as soon as he turns his cellphone back on, at which point he has the option of responding to you.
Friend Offline
ICQ gives you two options for sending text messages: standalone messages or within a conversation window you have with an existing buddy whose number you've input into his buddy list entry. When you send a message to an offline buddy, it automatically forwards to his phone as a text message if you have a phone number listed for him. If he's online, the message is sent to his ICQ screen name.