I get "wrong answer" for test №3:
2687809 17:47:13
28 июл 2009 kiriloff 1002 C# Wrong answer 3 0.109 1 129 КБ
Can you help me, what problem of this?

Please help, what is wrong answer?! I think that you should display input data of test and correct result, because users can't understand what trouble in this.
I propose to see my answer, because all tests that i think up works correctly:
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text;

namespace _1002
{
    internal class _1002
    {
        //public const string par = "7325732573257325\n5\nit\nyour\nreal\nreality\nour\n4294967296\n5\nit\nyour\nreality\nreal\nour\n-1\n";


        private const string notFoundAnswer = "No solution.";
        private const string space = " ";
        private static Dictionary<char, char> phoneNumberValues = new Dictionary<char, char>();
        private static NumberFormatInfo nfi = NumberFormatInfo.InvariantInfo;

        static void Main( )
        {
            string[] input = Console.In.ReadToEnd().Split( new char[] { ' ', '\t', '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries );
            //string[] input = par.Split( new char[] { ' ', '\t', '\n', '\r' }, StringSplitOptions.RemoveEmptyEntries );

            FillPhoneNumberValues();

            int i = 0;
            while( i < input.Length )
            {
                string number = input[i];
                //check last line
                int exitFlag;
                if( number.Length == 2 && int.TryParse( number, out exitFlag ) )
                {
                    if(exitFlag == -1)
                    {
                        break;
                    }
                }

                i++;

                int countOfWords = int.Parse( input[i], nfi );
                i++;
                string[] words = new string[countOfWords];
                for( int j = 0; j < countOfWords; j++ )
                {
                    words[j] = input[i];
                    i++;
                }
                Dictionary<string, string> wordsWithNumbers = FormNumbersForWords( words );
                FormAnswer(number, 0, wordsWithNumbers, new StringBuilder());
            }
            //Console.ReadLine();
        }
        private static Dictionary<string, string> FormNumbersForWords( string[] words )
        {
            Dictionary<string, string> wordsWithNumbers = new Dictionary<string, string>();
            for( int i = 0; i < words.Length; i++ )
            {
                string word = words[i];
                StringBuilder wordAsNumber = new StringBuilder();
                foreach (char letter in word)
                {
                    wordAsNumber.Append(phoneNumberValues[letter]);
                }
                wordsWithNumbers.Add(wordAsNumber.ToString(), word);
            }
            return wordsWithNumbers;
        }

        private static int FormAnswer( string inputNumber, int index, Dictionary<string, string> wordsWithNumbers, StringBuilder result )
        {
            foreach(string number in wordsWithNumbers.Keys)
            {
                if( index < inputNumber.Length && inputNumber.Substring(index).StartsWith( number ) )
                {
                    // append space if need
                    if( index != 0)
                    {
                        result.Append(space);
                    }
                    // append variant of word
                    result.Append( wordsWithNumbers[number] );

                    //end of input line and result formed correctly : write result and exit
                    if( index + number.Length == inputNumber.Length )
                    {
                        Console.WriteLine( string.Format( nfi, result.ToString() ) );
                        index = inputNumber.Length;
                    }
                    // continue to form result (index always less than inputNumber.Length - 1)
                    else
                    {
                        index = FormAnswer( inputNumber, index + number.Length, wordsWithNumbers, result);
                    }
                }
            }
            //if result contains words (with spaces) formed recursively
            string resultAsString = result.ToString();
            if( resultAsString.Length > 0 )
            {
                int spaceIndex = resultAsString.LastIndexOf( space );
                if( spaceIndex > 0 )
                {
                    // remove last word
                    result.Remove(spaceIndex, resultAsString.Length - spaceIndex);
                    return resultAsString.Length - spaceIndex;
                }
                else
                {
                    // clear result
                    result.Remove( 0, result.Length );
                    return 0;
                }
            }
            //result is empty so all variants are not consist for us
            else
            {
                Console.WriteLine( string.Format( nfi, notFoundAnswer ) );
                return inputNumber.Length;
            }
        }

        private static void FillPhoneNumberValues()
        {
            phoneNumberValues.Add( 'i', '1' );
            phoneNumberValues.Add( 'j', '1' );
            phoneNumberValues.Add( 'a', '2' );
            phoneNumberValues.Add( 'b', '2' );
            phoneNumberValues.Add( 'c', '2' );
            phoneNumberValues.Add( 'd', '3' );
            phoneNumberValues.Add( 'e', '3' );
            phoneNumberValues.Add( 'f', '3' );
            phoneNumberValues.Add( 'g', '4' );
            phoneNumberValues.Add( 'h', '4' );
            phoneNumberValues.Add( 'k', '5' );
            phoneNumberValues.Add( 'l', '5' );
            phoneNumberValues.Add( 'm', '6' );
            phoneNumberValues.Add( 'n', '6' );
            phoneNumberValues.Add( 'p', '7' );
            phoneNumberValues.Add( 'r', '7' );
            phoneNumberValues.Add( 's', '7' );
            phoneNumberValues.Add( 't', '8' );
            phoneNumberValues.Add( 'u', '8' );
            phoneNumberValues.Add( 'v', '8' );
            phoneNumberValues.Add( 'w', '9' );
            phoneNumberValues.Add( 'x', '9' );
            phoneNumberValues.Add( 'y', '9' );
            phoneNumberValues.Add( 'o', '0' );
            phoneNumberValues.Add( 'q', '0' );
            phoneNumberValues.Add( 'z', '0' );
        }
    }
}