Timeout issue when sending SMS via AT+CMGS

When I try to send text messages via "atcom AT+CMGS=\"my_phone_number\", \"CR\", \"Text message text\", I always get a timeout error. I'm able to send other AT commands without issue. I think the problem has to do with how atcom terminates the message stream, but I'm not certain what I need to change to fix this. Any help would be greatly appreciated!