Give CS a call on 150 and they will be able to tell you if you're authorised to have more lines / devices.
If you're looking for add to plan items or additional plans with devices then you can also log into your online account and check. If you're not, it'll give you a message to say you 'can't add more devices at this time'
If you're a new customer it can take a bit to build up an internal credit level with EE. Today the answer might be no but if you pay on time and by direct debit the options available will change.
