You can write a python code which will look something like this:
import boto3
# Create an SNS client
client = boto3.client(
    "sns",
    aws_access_key_id="ACCES KEY",
    aws_secret_access_key="SECRET KEY",
    region_name=us-east-2
)
topic = client.create_topic(Name="notifications")
topic_arn = topic['TopicArn']  
# Add SMS Subscribers
for number in list_of_contacts:
    client.subscribe(
        TopicArn=topic_arn,
        Protocol='sms',
        Endpoint=number  
    )
# Publish a message.
client.publish(Message="Good news everyone!", TopicArn=topic_arn)