Document:

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                                                                    EXHIBIT 4.51

No TD0196

                                 LEASE AGREEMENT

LESSOR: BEIJING GAOLING ESTATE DEVELOPMENT CO. LTD
LESSEE: BEIJING AIRINBOX INFORMATION TECHNOLOGIES CO., LTD.

The lessor is the owner of the Tenda Building, which the lessor agrees to let
and the lessee agrees to lease. Pursuant to the Contract Law of the People's
Republic of China and other relevant laws and regulations, two parties come into
a lease agreement as follows to stipulate the rights and obligations of the
lessor and lessee.

Article 1 Rental, Property Management Fee and Deposit

1.1  The lessor agrees to let the rooms on 8th Floor of Tenda Building to the
     lessee as office. The lease area of the rooms (hereinafter referred to as
     "Leased Rooms"), mutually confirmed by two parties, is 1548 square meters
     in total. (Appendix 1 of this Agreement is the ichnography of the Leased
     Rooms, which is used exclusively to confirm the location.)

1.2  The lease term is 1 year and 1 month, commencing from the 28th April 2006
     to 27th May 2007.

1.3  The rental is RMB 3.20 Yuan/day/Sq.M, while the Property Management Fee is
     RMB 1.00 yuan/day/Sq.M. Therefore the total fee for each month (including
     the property management fee) is RMB 195,048.00 Yuan. Every month is
     calculated as 30 days in this agreement. The rental and property management
     fee shall be paid monthly and prepaid every month, that means the lessee
     shall pay the rental and property management fee within 10 days before each
     payment period (payment period is from the 28th of one month to the 27th of
     next month) in RMB. The aforesaid fee will not be regarded as made unless
     lessor has received the payment. The lessee shall pay the lessor a delay
     fee, equal to two per ten thousand of the total due payment per day, if the
     lessee fails to make the payment according to payment period under this
     Agreement.

1.4  The lessor is entitled to adjust the rental and property management fee in
     the event that the lease term is more than 2 years.

1.5  The lessee shall give three months' rental and property management fee to
     the lessor as the guaranty for the performance of this Agreement
     (hereinafter referred to as "deposit"), which amounts to RMB 585,144.00
     Yuan, in words: five hundred eighty five thousand one hundred and forty
     four).

1.6  The lessee may terminate this Agreement by written notice to the lessor, in
     the case that the lessor fails to deliver the Leased Rooms to the lessee
     within 2 months from the commencing date of lease term not due to any fault
     or negligence committed by the lessor.

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     Under such circumstances, the lessor shall return the deposit, rental and
     property management fee, which have been collected, to the lessee (without
     charging any interest of the aforesaid fees).

1.7  The lessor is entitled to deduct the deposit in compensating lessor's
     losses and the delayed payment in case that the lessee violates the
     Agreement (including delaying the payment of rental, property management
     fee, compensating lessor's damages due to lessee's failure in performance
     of the agreement). When the amount of the deposit kept by the lessor is
     less than the amount prescribed herein in clause 5 after the deduction of
     rental therefrom, the lessee shall replenish it within five business days
     after receipt of a written notice from the lessor. Otherwise, the lessor
     has the right to take such measures as cutting telephone lines or power
     until the agreement is terminated. The lessee shall compensate lessor's
     economic losses resulted from deposit deficiency.

1.8  In case the lessee fully performs this Agreement, the lessor shall return
     whole deposit (without interest) to lessee within 30 days from the day when
     this agreement is expired, and the lessee returns the Leased Rooms and pays
     up relevant fees to lessor.

1.9  Without the permission of the lessor, the lessee cannot assign the right of
     claim for the return of the deposit to any third party or use it as a
     guaranty for lessor's debt.

Article 2 Termination by the lessee during the valid period of this Agreement

     With written notice to the lessor and paying the whole deposit, this
     Agreement can be terminated by the lessee during the valid period.

Article 3 The Equipment and Reconstruction of the Leased Rooms

3.1  The lessor shall furnish the rooms with the following equipment:

     1.   central air-conditioner, ceiling(including intake, automatic smoke
          sensor, gushing machine, daylight lamp and head lamp, etc)

     2.   220v electrical plug, communication circuitry, antenna plug for
          satellite TV.

3.2  In needs of making any fitments or reconstruction of the Leased Rooms, the
     lessee shall provide the lessor with blueprint and scheme of the fitments
     and reconstruction as well as the information on the construction
     enterprise and its personnel in advance. The construction enterprise is
     obligated to pay management fee, which is RMB 6.55 Yuan per construction
     square meters to the lessor. The construction can be commenced, provided
     that the payment of construction guaranty fee and management fee is paid by
     the construction enterprise. The lessor shall refund the construction
     guaranty fee to the construction enterprise, in case that, through lessor's
     checking and accepting, the lessor confirms the construction is completed
     based on the blueprint and scheme approved by the

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     lessor and no damages has been made to equipment or facilities of the
     Leased Rooms. The lessee shall bear the taxes for any additional fitments
     and equipment, regardless the account name on the bill or what kind of tax
     item shown on the bill.

3.3  In case that the lessee rents the beeline telephone number (the account is
     opened under the name of the lessor in the telecom company) from the
     lessor, who will bear the telephone fee instead of the lessee, the lessee
     shall pay RMB 5000Yuan/each line (in words: RMB FIVE THOUSAND Yuan each
     line) as deposit for the telephone fee and RMB 300 Yuan /Year/Line (in
     words:RMB THREE HUNDRED YUAN every year for each line) as circuitry
     maintenance fee. After paying the deposit for telephone fee and circuitry
     maintenance fee, the lessee may choose telephone number and the lessor is
     responsible for installing the telephone. The lessee shall pay each month's
     telephone bill within 7 days after receiving the notice from the lessor.
     The lessor shall refund the deposit of telephone fee without interest to
     lessee when the Agreement is expired; In case that the lessee brings the
     beeline telephone number itself or open an account under the name of itself
     in the telecom company, it shall pay the following fees in lump sum:
     circuitry occupation fee of RMB 200Yuan/each line (in words: RMB TWO
     HUNDRED YUAN each line), transfer fee of RMB 5 Yuan/each line (in words:
     RMB FIVE each line) and annual circuitry maintenance fee of RMB
     100Yuan/each line (in words: RMB ONE HUNDRED Yuan each line). The lessor
     shall assist lessee in installing the telephone.

Article 4. Renewal

After the expiry of the lease, the lessee has the right of priority to extend
the term of the agreement under the same conditions, provided that the lessee
notifies the lessor in writing three months before the expiry of the agreement.
The terms and conditions of renewal shall be negotiated by both parties (the
range for the adjustments of the price shall be made according to the increase
or decrease of the real estate index and the general leasing price of the whole
building). If the lessee does not notify lessor in the aforesaid period, it will
be regarded that lessee will not renew the lease of the Leased Rooms and shall
move out of the Leased Rooms before the termination date of the Agreement.

Article 5. The Return of the Leased Rooms

5.1  After the expiry of the agreement, the lessee shall return the Lease Rooms
     according to the time notified by the lessor. If the Leased Rooms cannot be
     returned on time for the reason on the part of the lessee and there is a
     new lessee, the lessor is entitled to request the lessee to leave the
     Leased Rooms in 3 days and deduct part of or entire deposit in compensating
     lessor's losses suffered from lessee's delay in returning the Lease Rooms.
     In case the deposit is not sufficient for compensating lessor's losses, the
     lessor is entitled to claiming for the insufficient part. If the Leased
     Rooms have not been rented to other lessees, it will be deemed by the
     lessor that the lessee will renew the lease of the Leased Rooms. In such
     circumstances, the lessee shall renew the lease of the Leased Rooms. If
     lessee refuses to renew the lease, the lessor will have the right to
     request the lessee to

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     move out of the Lease Rooms and deduct part of or entire deposit in
     compensating lessor's losses suffered from lessee's delay in moving out.

5.2  When the lessee return the Lease Rooms after expiration of the lease, the
     Leased Rooms shall be in good status(excluding reasonable wear and
     tear);the lessor has right to deduct the deposit to compensate
     corresponding reasonable losses when it finds that the rooms and equipment
     are damaged due to the reason on part of the lessee. In case the deposit is
     not sufficient enough to compensate lessor's losses, the lessee shall
     replenish the margin in case that the deposit is insufficient for the
     losses within 3 days after receiving lessor's written notice.

5.3  As to accession made by the lessee to the Leased Rooms (shall be approved
     by the lessor), the lessor is not supposed to request the lessee to restore
     the rooms to the original conditions. The lessor shall not pay the expenses
     back for the accession even if the lessee does not make the restoration.

Article 6. The Obligations of the Lessee

The lessee agrees to abide by the following provisions:

6.1  The lessee shall abide by all the rules and regulations stipulated by the
     lessor for its authorized agent. The detail content is in Appendix two
     "Client Handbook". The lessee shall strictly abide by the rules and
     regulations and can not reject without reasonable causes if lessor notifies
     lessee of all reasonable changes it made on the rules and regulations
     (adding or reducing clauses or revising). If inconsistency occurs between
     the Client Handbook and this Agreement as well as other appendixes, the
     concluded Agreement and appendixes shall prevail.

6.2  The lessee shall not or allow others to take any actions, which will make
     the insurance of the Lease Rooms and the building invalid or possibly
     invalid, or result in increase of the insurance premium. Otherwise, the
     lessee shall bear the corresponding increase of the insurance premium and
     other related expenses for repurchase of the insurance by the lessor due to
     lessee's violation of this clause. The lessee shall pay the aforesaid fees
     according to the period asked by lessor after the occurrence of lessee's
     violation.

6.3  The lessee shall not take the following activities

     1.   To utilize the Leased Rooms in illegal activities.

     2.   To assign the rights of lessee under the agreement to others or use it
          as security.

     3.   To lease part of or entire Leased Rooms to others or let others use
          the Leased Rooms.

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     4.   To use the Leased Rooms with a third party (not including affiliated
          enterprises of the lessee, which means the parent company, subsidiary,
          branch company of the lessee or the company which shares the common
          investment party and legal representative with the lessee) or show
          other's name as the lessee of the Leased Rooms.

     5.   To transfer the ownerships of the ornaments, equipment and articles in
          the Leased Rooms to any third party or use them as security.

6.4  The lessor shall take charge of the security during the lease term and be
     responsible for theft or damages of the articles in the Leased Rooms. In
     case of fire, the lessee shall make compensation to lessor if the fire is
     caused due to lessee's reason.

Article 7 The Obligations of the Lessor

The lessor agrees to abide by the following provisions:

7.1  The lessor shall guaranty the public facilities (including illumination,
     air-conditioner, automatic smoke sensor, sprinkle, W.C and elevator, etc)
     are in good status. The repair shall be made in time after trouble report
     is received from the lessee.

7.2  Implementing twenty-four hours' security measures to ensure the security of
     the mansion.

7.3  The lessor shall bear the corresponding losses suffered by the lessee due
     to quality problems of the Leased Rooms (excluding the matters stipulated
     in article 9 of this Agreement and the losses incurred due to the quality
     resulting from lessee's reconstruction).

Article 8 Damages and Breaching Liabilities

8.1  The lessee shall compensate the lessor for losses due to intentional
     actions or negligence of lessee or its agents, and employees in the
     performance of their duties. On the contrary, the lessor shall compensate
     lessee for losses due to intentional actions or negligence of lessor or its
     agents and employees in the performance of their duties.

8.2  If the lessee breaches the agreement as well as any of the appendixes and
     supplementary agreement and fails to make the rectification within 7 days
     from receiving lessor's written notice, the agreement is automatically
     terminated wihin 14 days after the written notice is issued. The lessee
     shall leave the house within 5 days from the issuance of the written notice
     after the agreement is automatically terminated; at the same time, the
     lessor is entitled to claim for damages with the amount of three months'
     renting fees and management fees; the lessee also agrees to bear losses and
     expenses incured. The lessor shall deduct the guaranty money for the
     compensation if the amount of the guaranty money the lessee has paid is the
     same as the damages. Otherwise, the lessee is obligated to

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     make up any shortfall. The measures prescribed here are not the sole
     measures and the lessor is entitled to take other measures in case of the
     breach.

Article 9 Exemption from Liabilities

The lessor is exempted from liabilities in the following cases:

1.   The temporary cease for the utilization of the public establishments for
     the necessary maintenance of the building and not due to the reason of the
     lessor.

2.   The losses the lessee suffers is incurred in the event of the earthquake,
     typhoon and other events which belongs to Force Majeure.

3.   The lessee suffers the losses due to the reason of other lessees or the
     third parties (but the lessor is responsible to assist the lessee for
     reimbursement from the infringers).

Article 10 Abandonment of the Rights

The abandonment of any right stipulated by the agreement shall be based on the
written signature of the lessor. The facts that the rental or other items the
lessee paid are insufficient to the amounts stipulated by the agreement, or with
the consent of the lessor, do not have any influence on the right of the lessor
to claim for the arrearage and the rights to take other measures according to
the agreement or laws and regulations.

Article 11 The Service of the Notice

All the notices required by the agreement shall be made in written form. The
invoices, bill of documents and other notices issued by the lessor to the lessee
shall be marked with the lessee as addressee. The written notice is regarded as
having served if it is delivered to the leased rooms, sent by the registered
mail or delivered to the address of the lessee in Beijing. The notice issued by
the lessee to the lessor will be regarded as having served if it is delivered to
the following address and accepted with signature: Beijing GaoLing Real Estate
Development Co. Ltd, No. 168, Xi Zhi Men Wai Avenue, Hai Dian District, Beijing,
China

Article 12 Disputes

The agreement shall be governed and interpreted by the law of PRC. Any party may
file the action to the people's court in the jurisdiction if the lessor and
lessee cannot settle the disputes which arise from the agreement with
negotiation.

Article 13 Business License and Language

The lessee shall produce business license and the authorization letter for the
authorized representative to sign the agreement on behalf of the lessee. The
copy of the duplicate of the

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business license and the original authorization letter will be attached to the
agreement. As an important part of the agreement, the appendix will be effected
at the same time and have the same legal effect with the agreement.

The agreement and its appendix shall be written in Chinese or English with the
same legal effect. The agreement has two original copies while the lessor and
lessee will hold one of them.

Article 14 Supplementary Agreement

The parties of the agreement can conclude supplementary agreement through
negotiation on other related matters. The supplementary agreement with the same
legal effect of the agreement will be annexed to the agreement as an important
part of the agreement.

The agreement shall become effective from the date of the affixation with their
common seals as well as the guaranty is fully paid.

Appendix One: Ichnography of the Leased Rooms
Appendix Two: <Clients Handbook>
Appendix Three: Supplementary Agreement

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(Signature Page)

LESSOR:    BEIJING GAOLING ESTATE DEVELOPMENT CO. LTD
ADDRESS:   NO. 168, XI ZHI MEN WAI AVENUE, HAI DIAN DISTRICT, BEIJING, CHINA
POST CODE: 100044

LEGAL REPRESENTATIVE (SIGNATURE): SUN JIANGHAI

TEL: 8838.3388
ACCOUNTING BANK: __________________________________
ACCOUNT NO.: ______________________________________
DATE: 2006-4-16

LESSEE: BEIJING AIRINBOX INFORMATION TECHNOLOGIES CO., LTD.
ADDRESS: __________________________________________
POST CODE: ________________________________________

LEGAL REPRESENTATIVE (SIGNATURE): WANG GUIJUN

TEL: ______________________________________________
ACCOUNTING BANK: __________________________________
ACCOUNT NO.: ______________________________________
DATE: 2006-4-16

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THE SUPPLEMENTARY AGREEMENT NO. 1 FOR <THE LEASE AGREEMENT > NO. TD0196
LESSOR: BEIJING GAO LING ESTATE DEVELOPMENT CO. LTD
LESSEE: BEIJING KONGZHONG XINSHI INFORMATION TECHNOLOGY CO. LTD

The lessor and lessee reach the following supplementary agreement as to < the
Lease Agreement > . No. TD 0196(hereafter simplified as <the Agreement>):

1.   Free Leasing Period: 60 days commencing from April 28th 2006 to July 27th
     2006. During the free leasing period, the lessee shall only pay RMB 1.00
     Yuan/day/Sq.M. as the management fee and other related fees. If <the
     Agreement >is terminated before the expiration, the free period after the
     termination date will not come into effect any more and the lessor shall
     not make compensation to the lessee. The lessee shall make up for all the
     renting fee according to the stipulated rental of <the Agreement> if <the
     Agreement> is terminated by the lessee before the expiration of the renting
     term.

2.   The item 6 of article 1 in <the Agreement> shall be revised that "The
     lessee may terminate this Agreement by written notice to the lessor, in the
     case that the lessor fails to deliver the Leased Rooms to the lessee within
     one month from the commencing date of the lease term. Under such
     circumstances, the lessor shall return the deposit, rental and property
     management fee, which have been collected, to the lessee. (without charging
     any interest of the aforesaid fees) The lessor pay a compensate, which is
     20% of collected deposit, rental and property management fee."

3.   The item 8 of article 1 of <the Agreement> shall be revised that "In case
     the lessee fully performs this Agreement, the lessor shall return whole
     deposit (without interest) to lessee within 30 days from the day when this
     agreement is expired, the lessee returns the Leased Rooms and pays up
     relevant fees to lessor. The lessor shall pay a delay fee to lessee, equal
     to two per ten thousand per day, provided that lessor fails to return the
     deposit on time."

4.   The article 2 of <the Agreement> shall be revised that "The lessee shall
     give written notice to the lessor in case that lessee terminates the
     Agreement."

5.   The lessee shall produce blueprint in advance to the lessor and get the
     consent from the lessor and the fire control department for carrying out
     the construction if the lessee plans to make secondary fitments and
     reconstructions to the Leased Rooms. The lessee should not tie up the fire
     control channels and alter the fire control subarea of the Leased Rooms.
     The modification for the liquid, ventilation and fire control system shall
     be carried out by the construction company appointed by the lessor, while
     related expenses shall be borne by the lessee.. The fitments and
     modification to the common area of the building should be restored to the
     original status at the time of its leave . All the expenses should be borne
     by the lessee.

6.   During the lease term the lessor shall provide lessee with 2 parking places
     in the second underground parking area in the Tenda Building without
     charging any fee. The term of free use the parking place shall be adjusted
     according to the term of <the Agreement>, provided

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     that there is any change with the term of <the Agreement>. If the term of
     <the Agreement> is expired or terminated before expiration, the lessor will
     not provide the aforesaid free parking place and relevant services to the
     lessee.

7.   The supplementary agreement is the supplements and alteration for <the
     Agreement> and has the same legal effect with <the Agreement> . This
     agreement will prevail as to any conflict between the supplementary
     agreement and <the Agreement> . Others will be executed by <the Agreement>.

8.   The agreement has two original copies while the lessor and lessee will hold
     one of them. The agreement is effective on the date of the subscription.

LESSOR: BEIJING GAO LING ESTATE DEVELOPMENT CO. LTD

LEGAL REPRESENTATIVE OR CONSIGNER (SIGNATURE): SUN JIANGHAI
DATE: 2006-4-16

LESSEE: ___________________________________________

LEGAL REPRESENTATIVE OR CONSIGNER (SIGNATURE): WANG GUIJUN
DATE: 2006-4-14

                                       10<PAGE>

                                                                    EXHIBIT 4.52

     SUPPLEMENTAL AGREEMENT NO. 1 TO THE PREMISES LEASE AGREEMENT NO. TD0196

Landlord:   Beijing GaoLing Estate Development Co. Ltd.
Tenant:     Beijing AirInbox Information Technologies Co., Ltd.

     The following amendment (the "Supplemental Agreement") to the Premises
Lease Agreement No. TD0196 (the "Lease Agreement") have been entered into by the
Landlord and the Tenant:

1. Rental Free Period: 60 days from April 28, 2006 to July 27, 2006.

     During the rental free period, the Tenant will not pay the rent except for
the maintenance fee and other related fees (RMB 1.00 yuan per square meter per
day). In the event that the Lease Agreement is terminated before the expiration,
any remaining part of the rental free period after the determination shall be
void and the Landlord shall not make any compensation to the Tenant for this
reason. In the event that the Tenant terminates the Lease Agreement before the
expiration, the Tenant shall pay the Landlord in full amount for any rental free
period the Tenant has had with the rental price set forth by the Lease
Agreement.

2. Section 6 of Article I of the Lease Agreement shall be revised as: In the
event that the Landlord fails to make the rental premises available to the
Tenant one month after the commencing date of the lease, the Tenant may
terminate the Lease Agreement by a written notice to the Landlord, who shall
return to the Tenant any deposit, rent and maintenance fee (without any
accumulated interest) and pay the Tenant a compensation amount equal to 20% of
such deposit, rent and maintenance fee.

3. Section 8 of Article I of the Lease Agreement shall be revised as: Upon the
expiration of the Lease Agreement if the Tenant has returned the rental
premises, paid all related fees and fully performed the Lease Agreement, the
Landlord shall return to the Tenant the full deposit (without any accumulated
interest) within 30 days. Any delay shall generate a 0.002% late fee per day.

4. Article II of the Lease Agreement shall be revised as: The Tenant may
terminate the Lease Agreement before the expiration by a written notice to the
Landlord provided that the deposit shall not be returned.

5. In the event that the Tenant plans to renovate or remodel the rental
premises, the Tenant shall deliver to the Landlord the work plan and acquire the
consents from the Landlord and applicable fire departments. Such renovation or
remodeling may not cause blockage of any fire exits or alter any original fire
control sectors. Any remodeling on the systems of water, ventilation or fire
control shall be undertaken only by contractors designated by the Landlord, and
all the expenses shall be taken by the Tenant. Should the Tenant has any
renovation or remodeling at any public areas on the floors of the rental
premises, the original condition shall be restored when the Tenant moves out of
the Tengda Tower and all the expenses shall be taken by the Tenant.

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6. During the lease period, the Landlord shall provide the Tenant two parking
spaces free of charge on second basement floor of the Tengda Tower. In the event
that the lease period set forth in the Lease Agreement is changed, the term for
the two parking spaces shall be changed accordingly. Upon the expiration or
termination of the Lease Agreement, the Landlord shall stop providing such
parking spaces and any related service.

7. As a supplement and amendment to the Lease Agreement, this Supplemental
Agreement is of equal legal effects. Should there be any conflict between this
Supplemental Agreement and the Lease Agreement, this Supplemental Agreement
shall prevail while all other provisions of the Lease Agreement shall remain as
effective.

8. This Supplemental Agreement shall have two original copies, with each party
hereto holding one copy. It shall become effective upon the execution by each
party hereto.

Landlord: Beijing GaoLing Estate Development Co. Ltd.

Legal Representative or Trustee: Sun Jianghai (Signature) (Corporate Seal)
Dated: April 16, 2006

Tenant: Beijing AirInbox Information Technologies Co., Ltd.

Legal Representative or Trustee: Wang Guijun (Signature) (Corporate Seal)
Dated: April 14, 2006

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