Mike's PBX Cookbook

Meridian BARS Programming:
Third-Party Cellular Gateways (GSM Gateways)

Introduction

GSM Gateways provide direct trunk access to the local cellular network. These gateways are external devices that provide direct access between the PBX and the local cellular provider's network, bypassing the local switched network. This makes the call appear to the network to have originated from another mobile of the same network, so it enjoys a cheaper call rate.

The PBX must be programmed to route calls to cellular numbers via the gateway device. Trunk access codes (ACODs) can be used to do this, but users must remember to use the appropriate ACOD, depending on the call type. The preferred solution is to automatically route the call by analyzing the digits dialed. This is accomplished by implementing Basic Alternate Route Selection (BARS) feature through the programming of a Special Number (SPN) translation data blocks for each code prefix.

Routing Calls to Cellular Gateways

The following process will help guide you through programming the routing of calls made to cell phone numbers on a Meridian switch where BARS is already in effect, as indicated by LD 86 ESN, AC1 = 9 (or any other number).

Process steps -

1. Identify all numbers targeted for routing to the gateway device and compare these to existing SPNs.
These numbers must include all digit(s) used locally to access cell phone numbers, such as a leading "0" followed by a cellular prefix. These numbers would not include the "9" used to access BARS as that is stripped off by the PBX automatically.

Print LD 90 (NET/AC1/SPN).
Look for any SPNs that may already be associated with these targeted numbers.
If there are already SPNs covering the range of these cellular numbers, determine whether there are any landline numbers that are also covered by those SPNs.
Make a list of the SPNs required for the cell phone number sequences and for any landline numbers.

e.g. In this example from a LD 90 printout, if your cellular dialing sequence starts with "051", you would determine whether there are any landline prefixes also starting with "05". 

SPN 05
FLEN 0
INPL YES
RLI 3
SDRR NONE
ITEI NONE

2.  Determine if Digit Manipulation is required.
If Digit Manipulation is required, create a Digit Manipulation Index (DMI) table in the DGT block using LD 86.
Print DGT, LD 86 to find an unassigned DMI number.

Prompts and responses for DMI creation follow -

>LD 86
REQ NEW
CUST 0
FEAT DGT
DMI 1-255             cannot be 0
DEL x..x              number of digits to delete, NOT the actual digits. <CR> if not needed
INST x..x             actual digits to be inserted.
                      <CR> till end of LD 86

3.  Determine Route List Index (RLI) requirements for the list of routes where you want to send the calls to cellular numbers.
Print RLB, LD 86.
Note the current RLI settings for landline calls (as determined from LD 90 SPN list printed above), particularly Route assigned, FRL, DMI, and next available RLI number.
Identify Route number assigned to gateway device (LD 21, RDB).

4. Create a new Route List Index (RLI) for calling cell phone numbers.
This RLI should have at least two entries -
Entry 0 should point to the Route created for the cellular gateway device, and Entry 1 should point to the PTT city trunk or landline used for external calls from Post.

>LD 86
REQ NEW
CUST 0
FEAT RLB
RLI x                use next available RLI identified in Step 2
ENTR 0               routing to Gateway
LTER
ROUT x               insert route number leading to gateway device
TOD 0
EXP
FRL x                0 for no restrictions, or use the FRL assigned to current landline RLI
                     <CR> up until DMI field is displayed
DMI x                enter DMI if required as built in Step 2 above
                     <CR> to next ENTR
ENTR 1               routing to landline
LTER 
ROUT x               insert route number leading to landline
TOD 0
EXP
FRL x                0 for no restrictions, or use the FRL assigned to current landline RLI
                     <CR> up until DMI field is displayed
DMI x                enter DMI if required as built in Step 2 above
                     <CR> till end of LD 86

5. Remove (OUT) any SPNs that cover both landline and cellular.
These SPNs must be removed (OUT'ed) before new, more specific SPNs are created to cover the different numbers. Be advised, that in the interim between removal and build, calls via BARS to these numbers will not be passed through the PBX. So it is recommended that you not remove the existing SPNs until you are ready to start sending calls through the gateway devices.

For the example above, SPN 05 would need to be OUT'ed, and 10 new SPNs need to be created (050, 051, 052, 053, 054, 055, 056, 057, 058, 059). 

>LD 90
REQ OUT
CUST 0
FEAT NET
TRAN AC1
TYPE SPN
SPN 05

6. Create new SPNs to cover cellular and landline numbers.
For the above example, SPN 051 as the leading digits of a cellphone number would be associated with the new RLI built in Step 4 above. The other 9 SPNs noted above would be populated with RLI 3, which was associated with the previous landline SPN 05.

Examples follow - 

>LD 90
REQ NEW
CUST 0
FEAT NET
TRAN AC1
TYPE SPN

SPN 050
                <CR> to RLI
RLI 3
                <CR> to next SPN prompt

SPN 051
                <CR> to RLI)
RLI x           (enter RLI built in Step 4
                <CR> to next SPN prompt

SPN 052
                <CR> to RLI
RLI 3
                <CR> to next SPN prompt. Continue until all SPNs are built

Conclusion -
The system will now route all calls to cell phones through the gateway device. If the trunks are busy, the call will fallback to the landline and should still reach the cell phone.

Be aware that if the gateway devices fail or lose power, the PBX will not be aware of this and may continue to attempt to route calls unsuccessfully. Check out SBOC (Step Back on Congestion), RRA (Reroute all), to pass calls to the next RLI entry in this case.