Is a divorce valid with the words "you are divorced" after legitimate seclusion and pregnancy without the family's knowledge, and what is the ruling on the 'iddah (waiting period) and its duration, or is 'iddah not obligatory and a new contract is required?

If the husband intends divorce by a mobile phone message after the wife requests it, it constitutes a revocable divorce (ṭalāq rajʿī), and the wife is entitled to the waiting period (iddah) and the dower (mahr). The husband has the right to take his wife back before the expiry of her iddah without the need for a new contract or her consent. However, if the iddah expires, he cannot take her back except with a new contract. The iddah ends with childbirth.