Missionaries try to keep an active turnover, and time lost following up disinterested contacts is time that could be spent teaching other people. Preparing the contact as much as possible is absolutely crucial. The best possible situation is when the person is willing to initiate contact with the church himself or herself, because this shows a much higher level of interest than simply accepting visits. Please give the contact person the phone number and address of the appropriate mission office if possible and explain that because mission offices are open generally only during working hours and take time off for conferences and preparation days, they may have to call several times to get through. Many of these referrals were written by individuals who were excited about meeting someone from Russia, but did little to familiarize them with the church.
Referrals can be very helpful if they are appropriately prepared.
If the person has not expressed a real interest in the church, it is more appropriate to continue working with the person rather than send it on as a referral for someone else to do the work. If people aren't genuinely excited about the church when they talk to a person who they know, it is very unlikely they will react positively to missionaries who they don't know. Submitting names of people without their knowledge and active interest is generally disapproved of by missions and may offend the contact as well. The person may or may not have a phone, but if they do that is important information since public transportation can be is poor and sometimes missionaries can give up on referrals who are consistently not home, especially when they live in an inconvenient or distant location. It is a good ice-breaker when missionaries know the name of the person who submitted the referral and can use that to bring back memories and build a common ground.