Although I can't speak specifically to FL civil procedure rules, most states have very similar rules. You can object to having the witness appear by phone. But ultimately, the issue is in the judges' discretion.
In CO, for example, a party may make a Request of Absentee Testimony (e.g. testify by phone), the other party must object to the request within 3 days. The preference is to have people testify in open court, it not absolutely mandatory and most court rules give the judge the discretion to decide.
In small claims court, the procedure is less formal.
In order to avoid a trial, very often the Debt collector's attorney will file a motion for summary judgment. Unless you have crafted your pleadings very carefully, the decision will be made without a trial. Hope this perspective helps!
You should visit with a qualified consumer attorney in your area. Lots of collectors sue with inaccurate or incomplete information. If there is an error on their pleadings, there may be an FDCPA violation.