Can I add a number from another service provider as a one touch call or to the whitelist ?

Yes you can add numbers from other service operators in the one touch call feature.

Family Tag Features
How do I buy the device ?
What are the features of the device ?
Can I buy more than one devices at the same time ?
How do I get the Device ?
Can I add more than one number to the One Touch Call feature ?
What is One Touch Call (SOS) Feature ?
Can I whitelist numbers on other networks ?
What is a Whitelist ?
How many numbers can I add to the whitelist ?
What is the Time Interval Mode ?
What is a geo fence ?
What will happen if I change the device name ?
What is the Vibration Mode ?