Yes, you can keep your old number.
However, it is CRITICAL TO KEEP YOUR EXISTING CELLULAR ACCOUNT OPEN until you have successfully transferred your cell phone number across to the Solavei™ network. If you do not do so, you could lose your existing number, so this is an important step to remember.
Once you receive the Solavei SIM card which is compatible with your cell phone or you have purchased a new Android phone from Solavei, then instructions will be sent by email to explain how to transfer your cell phone number across from your old network to the Solavei network for use with your phone. After the number has been successfully ported across, then it is safe to cancel the service with your old cellular carrier.
If you have a phone through AT&T or T-Mobile, then you can use your exiting phone. Most of AT&T and T-Mobile phones are GSM phones which are compatible to the Solavei network. Verizon, Sprint, Boost Mobile phones run on CDMA technology and will not work on the Solavei network. It is possible to unlock the Sprint and Verizon Iphones. You will need to use a SIM card modification tool found here: www.gevey.com
Please if you have any GSM phone, they must be unlocked to work once you get your Solavei Sim Card.
With the iPhone, you will be able to use a Solavei SIM card and get a quality voice and text experience with data at 2G / EDGE speeds.
A complete list of the currently supported phones is available from this link here. Solavei Support Phones.