How many times have you experienced, or witnessed, this REAL tongues and was it glossolalia or xenolalia?
God isn't a "One trick pony", and just to straighten some things out - NO MAJOR PENTECOSTAL DENOMINATION connects "Tongues" with Salvation - PERIOD. "Oneness Pentecostals" (UPCI) do - but they've got other theological problems as well.
My definition of "Real tongues" would be that which the Holy Spirit gives you directly without any Creative input on your part - i.e. the Holy Spirit gives you the "words" to say, and you simply speak them. Whether they are a KNOWN language, or not, I wouldn't know, and couldn't care less.
SInce I have NEVER spoken in tongues in the public venue as a "message to a congregation" I would be one that according to Paul's definition DOESN'T SPEAK IN TONGUES, although I do it in private (1 cor 14:4) mode.
My Public gift has been Interpretation of tongues, which works just like tongues, except that the utterance in in the common language.
Essentially "Tongues", "Interpretation of Tongues", "Prophesy", "Word of Wisdom", and "Word of Knowledge" are all the SAME GIFT only varying in content. The same goes for Mat 10:19 which is a "prophetic" manifestation.
I reject the theory that they are "Angelic languages" since Paul was probably only using the term as emphasis in 1 Cor 13:1. That they are SOMETIMES known languages is a matter of record (unless you're convinced that all Pentecostal pastors workers and Missionaries are liars).
That the "Tongues" spoken in Acts 2 were known languages is the LEADING (and probably the correct) interpretation, although there's an undercurrent of "Miracle of hearing" advocates.
In the Corinthian case, apparently, NO KNOWN LANGUAGE was in evidence, and without "Interpretation" nobody knew what was being spoken.
There's ALSO EVIDENCE in 1 Cor 14 that people were "SHOWING OFF" with their prayer languages (MY gift is better than YOUR gift),
This is BECAUSE if the Holy Spirit burdens a person to speak in tongues publicly, He'll also burden somebody to Interpret. If there ISN'T an Interpretation, then the spoken tongue was "out of order", and not a legitimate spiritual manifestation.
Historically, NO HUMAN, except for Jesus, had been indwelled by the Holy Spirit. all through the OLD Testament, people were "Endued with power" by Him, but as Jesus said "you KNOW him, because He has been WITH YOU, but he SHALL BE IN YOU (john 14:17). THAT happened at John 20:22 when Jesus breathed on them the effect being in Luke 24:45 when their understanding was "opened".
Acts 2, however is referred to by Jesus as an "Enduement" (a clothing with) power. SO people aren't "getting the Spirit twice", the Holy Spirit is simply coming ON people as He did in the O.T. that He's already IN. the obvious manifestation on that occasion was people speaking in languages that they SHOULDN'T HAVE KNOWN. the obvious manifestation in Acts 10, and 19 was: they spoke in tongues and spoke prophetically.
SO - the ONLY manifestation of "tongues" that I PERSONALLY have experienced is that of private use. Whether it's a "Known language" or not, I wouldn't know.
What's a matter of record in the Assemblies of God Denomination (that I'm part of) is:
Tongues in the private setting - no "message" implied (1 Cor 14:4).
Tongues in the Public setting - not understood, but interpreted by the Tongues speaker, or somebody else (In some cases by me). This is the MOST COMMON.
Tongues in the public setting that ARE understood by an individual listener or a group, often in the correct regional accent - AND sometimes also interpreted by another matching the content of the tongue.
A Message given in the Common language, and HEARD/understood in one or more different languages.
There's also a FALSE practice in Pentecostal churches (including the AG) called "Priming the pump".
I.e. you're encouraged to speak baby talk or nonsense syllables, or just to make sounds to "Get it started". This will result in PHONY TONGUES produced by your own mind that you have to "Practice" to get right.
REAL tongues don't require any sort of "Practice". They're just THERE In your mind, and you speak them as they flow in.