RLP issues: connecting two GSM modems | Telit Cinterion IoT Developer Community

Hello If somebody could give me a clue on this problem I’m facing, I will be very grateful. I am facing unexpected problems while trying to connect two GSM modems (Cinterion MC55i). To troubleshoot this I decided to test the modems with PCs (a PC-to-PC connection using the modems as interface). And the results where: - When the remote modem awnser the call and establish the connection, both DTEs are informed by the modems (and at the same time) with the message “connect 9600/RLP” - I Only have a 60% (aprox) of successful data connection (and this is my problem … ) - The connection failure is always on the calling modem, because the RLP does not go up (and link to the GSM (and) the remote/called modem) - The RLP on the “remote”/called modem goes always up, even in the case when the calling modem side didn’t managed to activate the RLP - The calling modem hangs with the message “no carrier” Main configuration settings: S0:001 S3:013 S4:010 S5:008 S6:000 S7:060 S8:000 S10:070 S18:000 +CBST: 7,0,1 +CRLP: 61,61,78,6 +CR: 0 +FCLASS: 0 +CRC: 0 +IPR: 0 +COPS: 0,0,"P xxx" (I used “xxx” for obvious reasons) +CSNS:4 If the full connection is fulfilled (RLP up on both sides) then it remains stable and I can transfer the amount of data that I want. So far I decided to complaint to the GSM operator; the services in the contract are voice and data (3G) Thanks in advance PS: since a timming sequence of the events might help, here they are: t0: dialing at the PCs Hyperterminal (ATD xxxx) and "enter" t0+7sec. -> the remote modem awnser; t0+22sec -> RLP established on both modems (if successful) t0+298sec -> RLP goes up on the remote modem when the calling modem does not have RLP up, which is odd