Can I add more than one phone number as "TO" number in "Twilio" trial version so that I can make sms / call to any of these numbers?

Question

I am using twilio trial version, I have registered using my mobile number lets say 123456. So twilio has added this number as my caller ID or "TO" number and I can only send message / call to this number. Now I want to try another number as well, like 787878, but it is not letting me add this number as its mentioning that "only verified numbers" can be used as a "TO" number. So I decided to add this number here in screenshot "TO" number image (note: existing one is the number with which I made Twilio account) but to verify, it is not sending me verification code on mobile via sms, is there any restriction that we can use only one number in trial account? Or can I use another phone number as a "TO" number as well? If it is so, then can I remove old number and then will I be able to add the new one?