SIMCom DSDS
Solution Introduction
The global leading provider of M2M wireless module
September, 2012
DSDS Overview
z DSDS = Dual SIM Dual Standby • Single modem (1BB / 1RF ) managing 2 SIMs
• Idle Services on both SIM in parallel (paging reception, reselection..) • Cell selection/reselection on the 2 SIMs
• Paging monitoring on 2 SIMs
• Ability of doing CS/PS call on any of the 2 SIMs
• BUT only 1 connection (CS/PS) at a time AND no activity on other SIM possible (neither idle nor connected)
• When 1 SIM enters CS/PS call => no activity on other SIMs
• MT call on second SIM not possible
• MO call on second SIM not possible (ie double call feature not possible)
z To sum up => Dual SIM, Dual Standby but Single Call
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Hardware Overview
∙ Only 2 SIM connectors are required
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Software Architecture Overview
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Software Architecture Overview
z Single L1 managing services for both HL stack
z protocol stack duplicated
z New module creation for Hw SIM swap management —
DSCV
z Suspend-Resume mechanism in case of concurrent
procedure —DSUAL
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AT Interface
• AT*PSSDS (Select default SIM)
– Set SIM_x into Default SIM
Description
Command
Possible Response(s)
Select SIM
*PSSDS=x
<SIM_x>
*PSSS?
<default SIM>
*PSSS=?
< default SIM>, <number of SIMs>
Clarification: If there are 2 SIMs, then the SIM1 is identified by value 1 and
SIM2 is identified by value 2. If there is one SIM then default SIM is the only
SIM present
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Use Cases
• Outgoing call on Default SIM: No Change
– By default, usual AT commands are routed to default SIM
Channel 1
atd0123456789;
OK
ATH
Channel 2
Direction
Comment
TEÆME
Dial “0123456789” for
speech call
ME -> TE
Hangup the Call
OK
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Use Cases
• Outgoing call on Non Default SIM
– Non Default SIM selection is needed before each command
Channel 1
Direction
Comment
AT*PSSS
TEÆME
Select SIM2 to make call from
SIM2
OK
MEÆTE
atd0123456789;
TEÆME
OK
MEÆTE
AT*PSSS
TEÆME
OK
MEÆTE
ATH
Channel 2
Dial “0123456789” for
speech call
Select SIM2 to disconnect the
call on SIM2
Hangup the Call
OK
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Use Cases
• Incoming call on Non‐Default SIM
Channel 1
at+clip=1;+crc=1; *psccdn=1
Channel 2
OK
+DSCRING: VOICE
+DSCLIP:
"0243411331",129,"",128,,0
+DSCRING: VOICE
+DSCLIP:
"0243411331",129,"",128,,0
Direction Comment
TEÆME Enable CLIP urc
Extended cellular result code
Call Connection and
Disconnection enabled
Note that these settings apply to both the SIMs
MEÆTE
MEÆTE Incoming voice call from SIM2
5 seconds between rings
+DSCRING: VOICE
+DSCLIP:
"0243411331",129,"",128,,0
AT*PSSS
MEÆTE
+DSCRING: VOICE
+DSCLIP:
"0243411331",129,"",128,,0
TEÆ ME Select SIM2 to answer the call from SIM2
OK
ATA
*DSPSCALL: 1,1,”0243411331”
MEÆTE
TEÆME
MEÆTE
OK
AT*PSSS
MEÆTE
TEÆ ME Select SIM2 to hang up the call
OK
ATH
OK
MEÆTE
MEÆTE The call is disconnected
MEÆTE
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Usage Summary
z No extra Hardware Circuit
z Simple AT command to change default SIM card
z SIM URCs on the non-default SIM are appended with
“DS” to indicate TE that this URC is from the non-default
SIM
• Incoming call notification from Default SIM: RING
• Incoming call notification from Non Default SIM: RINGDS
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Thank you!
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