All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The marital relations are very significant in Islam, so much that Allah considered it a strong covenant. Allah Says (what means): {... and they have taken from you a firm and strong covenant?} [Quran 4: 21]
Islam enjoins Muslims to announce the marriage contract, recommends holding it at mosques, and permits them to beat the Duff (percussion instrument consisting of a single drumhead of skin stretched on a circular wooden frame) at wedding parties and celebrate the occasion of the marriage.
In fact, all the above rites should be performed along with fulfilling the compulsory conditions of a marriage, that are the consent of a guardian of a bride, two trustworthy witnesses and bridal money.
Also, the claim of the husband to divorce is not accepted unless two witnesses testify to it because it is only him who can invalidate the marriage contract. Allah Says (what means): {And take for witness two just persons from among you (Muslims)…} [Quran 65: 2]
Therefore, after establishing a marriage contract as in the mentioned case, it is not considered null unless two trustworthy witnesses confirm the divorce. So, an approval by phone in clear words on its own is not sufficient, let alone unclear words.
Therefore, this woman is still bound by the marriage contract, so proposing marriage to her is forbidden, and it is forbidden for her to marry unless she gets divorced from her present husband.
If the husband is absent and his wife is suffering from his absence, since he is not bearing the expenses of his wife or he is not fulfilling the rights of his wife, then, in this case, she should present her case to an Islamic court if it is available. Otherwise, she should consult an Islamic center or Muslim authorities in her area to solve her problem according to the Sharee'ah. If their decision is for a divorce, it will be valid, and after ending her waiting period, the woman can marry anyone of her choice while fulfilling the conditions of a valid marriage. Before this procedure, she is considered a married woman and she cannot be proposed for marriage.
Allah knows best.