Yes, you can move your number to another network if you choose to leave GoMo.
If you cancel within your 14 day cooling off period your cancellation will take place from midnight on the day you cancel. You must move your number to another network before this goes through in order to keep your number.
If you cancel outside your 14 day cooling off period your cancellation will take place from your next billing date. You must move your number to another network before your next billing date in order to keep your number.