Mary, we have had some good solutions but for more targeted groups. For example, we have used LexisNexis's Accurint product for skip tracing (ie, finding phone numbers or alternate mailing addresses) for delinquent accounts. We have used the marketing website LeadsPlease.com to get contact information for specific demographic groups in our city/ZIP code. These projects have definitely been worthwhile. They are faster and cheaper than what we could research on our own. Getting phone numbers for 100,000 accounts is a lot bigger than what I've dealt with, but I would suggest you approach it as though you were a business doing a marketing campaign. They should be able to generate a file to your specifications and maybe your software provider could do some programming to allow you to import that data.