"in to" is the correct choice for your sentence. The fact that you can 
separate "in" from "to" in "put in calls to the Senate office" shows 
that the single-word form is inappropriate here. I get a very concrete 
reading of "put calls into", a sort of "install calls" reading that 
doesn't make much sense in the usual context for a sentence like this.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Johanna Rubba   Associate Professor, Linguistics
English Department, California Polytechnic State University
One Grand Avenue  • San Luis Obispo, CA 93407
Tel. (805)-756-2184  •  Fax: (805)-756-6374 • Dept. Phone.  756-2596
• E-mail: [log in to unmask] •      Home page: 
http://www.cla.calpoly.edu/~jrubba
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