HLR lookup is the process of getting mobile real time information. This includes roaming network, roaming country and roaming area. Along Hlr is lookup also important for cleaning database of the mobile subscribers by getting mobile number status as HLR in lookup result. The MNP or mobile number portability information can also be derived from the hlr lookup result. The result have IMSI. From IMSI the current serving mobile network operator can be derived. The basic ss7 network is used for lookup by the telecom mobile operators. For Details. https://www.cspsprotocol.com/what-is-hlr-lookup/

1. HLR Lookup
BY lookup get IMSI and Roaming
Information for a Mobile Number

2. HLR Lookup Response (Success)
• IMSI of subscriber
• Visiting MSC
• MCC and MNC of roaming network.
• Subscriber Status (Success/Failure).
• Number Portability Information Can be
derived by looking on IMSI and MSISDN.
• Name of the mobile operator the current
number belongs to.

3. HLR Lookup Response (Failure)
• Subscriber is not configure for SMS Teleservice
(MT-SMS).
• Subscriber is not attached.
• Query Timeout.
• SMS service is barred.
• Protocol Level errors or provider errors.

4. HLR Lookup Benefits
• Least Cost Routing: As a result of lookup, the bulk sms service provider
gets the location information (visiting country and visiting network). A low
cost route or network connection provider can be chosen for sending sms
to the mobile subscriber.
• Marketing database cleanup: While sending sms to a mobile , the
subscriber may be not present permanently. To send this subscriber
message again and again incur a cost and there is no outcome for
business. HLR lookup service provides status code for a subscriber if
lookup fails. If error is permanent failure ( e.g Unknown Subscriber) the
database can be cleaned for this subscriber.
• Billed the correct mobile operator, from lookup result, the mobile
number portability information can be obtained. A lookup service provider
can send CDRs for billing to the correct mobile operator.

5. HLR Lookup Benefits
• Save cost, by using a more cleaned accurate mobile number
database , a lookup service use can save cost. There are
organizations e.g Colleges or Universities , do very regular
messaging to thousands of alumni members. Lookup services
cleans the database for inactive numbers , this saves
thousand of dollars.
• Real Time Information, Hlr Lookup , provides real time
information for roaming, this enables the service user to plan
advertisement according to the roaming places.
• Use by Voip provider, A voip provider e.g Skype , can make a
lookup before terminating call to the roaming device. The
information collected can used to setup a low cost call route.

6. HLR Lookup Network
HLR
Lookup
Gateway
HLR
MSC/VL
R
HLR
Looku
p App
BSC
/BTS

7. HLR Lookup Network
• BTS : Base Transceiver Station is equipment or node in GSM
network , having antenna for wireless connection between
BTS and mobile device
• BSC: Base Station Control , controls the BSCs and allocates
the radio resources for a Mobile device. The handovers
between cells are controlled by a BSC.
• MSC: Mobile Switching Centre, is the node which connects a
wireless network to the rest of the PSTN
• VLR: Visitor Location Register, is the database in roaming
network. Which is present with a MSC..
• HLR: Home Location Register, is the database in home
network of a mobile operators which controls the
subscription of a mobile device.

8. HLR Lookup Call Flow
HLR
HLL Lookup
App
HLR Lookup
GW
Hlr Lookup Api
Request (HTTP)
SRI-SM –RESP (SS7)
Hlr Lookup Api
Response(HTTP)
SRI-SM (SS7)

9. Thanks
• For Detailed Tutorials please check on
• https://www.cspsprotocol.com/