I just completed a nice long detailed reply and my browser crashed... so you will have to get the abbreviated version.....
You have two choices here:
1) File in Texas (lots of problems with this option):
You will have to get a Texas court to accept an out-of-state service (unlikely) then have the defendant served in Iowa. The defendant will either ignore the service (most likely) and you get a default judgment (almost worthless-see below). Or, the defedant will file a Motion for Dismissal due to Lack of Jurisdiction (possible) and it would probably be granted. So, you are either DOA with the motion, or you have a default judgment. Assuming the debtor has no assets in Texas, you will have to domesticate the judgment to Iowa, where the defendant gets ANOTHER chance to void your judgment... on HIS turf. If the Iowa court sets a hearing on his motion to dismiss, you will have to appear... in Iowa.
Or
2) You can contact the courts in Iowa to see if they will accept your case from Texas... AND if they will allow a 'long distance phone trial' (personally, I doubt that they would). And even if they do allow it... your case would have to be based on IOWA statutes and Iowa Rules of Court!! Do you feel comfortable arguing those laws?? And it is possible that the claim you are making (valid under Texas laws) may be entirely different under Iowa laws!!
Default Judgment:
The judgment from Texas isn't DIRECTLY recognized by any Iowa authority. This means that you would have to 'domesticate' your Texas judgment into the Iowa judicial system, then get an Iowa judgment that you could use to enforce against the debtors assets in Iowa... using Iowa laws.
Finally, Iowa's 'Judicial Magistrates Court' limit is $4000.00.
http://www.judicial.state.ia.us/about/descript/district.asp