ANSWER: The only place in the New Testament where Immanuel (Emmanuel) is used for Jesus is in the gospel of Matthew. The term is used after Joseph's betrothed wife Mary returns to Nazareth after a three-month visit with her cousin.
Joseph discovers she is three months pregnant and concludes she has committed adultery. As he is mulling over what he should do, an angel tells him in a dream not to fear staying married to Mary (Matthew 1:20). Matthew then inserts his comments (and not the words spoken by an angel) regarding the meaning of Immanuel as it relates to Jesus.
Now all this came to pass, that it might be fulfilled which was spoken by the Lord through the prophet, saying, "Behold, the virgin shall be with child and shall give birth to a son (Jesus), and they shall call His name Emmanuel (Immanuel)"; which is, being interpreted, "God with us" (Matthew 1:22 - 23, HBFV throughout)
The prophet quoted by Matthew, in regard to the prophecy concerning the birth of Jesus, is Isaiah. He is the only person, in the entirety of the Old Testament, to use the term Immanuel. He stated, "Therefore, the LORD Himself shall give you a sign. Behold, the virgin shall conceive and bring forth a son, and they shall call His name Immanuel" (Isaiah 7:14, see also 8:8).
Bible translations vary regarding the term used for our Savior in Matthew 1:23. Most of them, like the NIV, NKJV and HCSB, use the original Hebrew word "Immanuel" (Strong's Concordance #H6005) written by Isaiah. Others, like the HBFV and the venerable KJV translation, use "Emmanuel" (Strong's #G1694), which is the Greek form of the word.
Mary is told directly, by the archangel Gabriel, what to call her firstborn son (Luke 1:31). Joseph is also directly informed, by an angel, what the name of the child should be (Matthew 1:21). There is no command for Mary or Joseph to call their miraculously conceived child anything but "Jesus" (Greek Iesous, Strong's #G2424, derived from the Hebrew "Joshua" which means, "Jehovah is salvation").
Notice again Matthew 1:23 and Isaiah 7:14. These verses say "they" shall call the one born "Immanuel." It does not say his sole personal name would be this. The "they" in these verses refers to one of the most important ways other people, throughout history, would refer to Jesus. The Bible itself contains no less than 125 references used to designate God the Father, Christ or both.
The word Immanuel tells us a great deal about Jesus. His virgin birth more than 2,000 years ago marked one of the greatest miracles EVER. "God with us" means just that, that one member of the Godhead willingly divested himself of his glory (John 17:5), riches (2Corinthians 8:9), his perfect pain-free existence (1Peter 2:21 - 24) and so much more to live as a human and offer himself as a sinless sacrifice for us. This glorious fact is confirmed by the apostle John, an eyewitness to Christ's entire ministry, in John 1:1 - 3 and verse 14.
The name "Immanuel" (Emmanuel) also alludes to a time when Jesus and God the Father will be permanently "with us," his greatest creation. Our heavenly Father will personally build a New Jerusalem, at the end of the Millennium, and place it on the earth. His eternal throne, and the throne of our Savior, will be in it and be accessible to all those humans who are saved (Revelation 21:22 - 26).