Region : Argentina

Model : TL-WR1043ND

Hardware Version : V1

Firmware Version :

ISP :

Region : UnitedKingdom

Model : TL-WR841N

Hardware Version : V7

Firmware Version : 3.13.9 Build 120201 Rel. 54965n

ISP : Avonline / Tooway

I have searched the forum, but cannot find any reference to this problem.

I can successfully make and receive VoIP calls via a Cisco SPA 303 IP phone, my iPhone 4S and a sogtphone on my MacBook PRO, using both DrayTEL and Sipgate as ITSPs. The Cisco phone is one of seven connected through the 3CX PBX software; but the iPhonne and the MacBook bypass the PBX and connect directly to the ITSP via the TP-Link router and the staellite modem.

However, when I try to make or recive a second (simultaneous) call, both calls start breaking up.

This happens both with the Cisco phones and with the iPhone and MacBook; so it's not a problem with the Cisco phone or with the 3CX soft PBX, since neither of these is involved when using the iPhone and the MacBook.

I have tried various port forwarding configurations over the last few weeks, but still the problem persists. The current forwarding arrangement is ports 5060-5080 and 5090 and 9000-9049 for the PC running the 3CX software, and ports 5160-5180 for the MacBook. The iPhone has sipgate.co.uk set as both the Local and the External PBX IP, and the PBX port is 5060. The Local SIP port is 5964 and the Fisrt RTP port is 4000.

Have I given enough infor to spark an idea in the mind of someone sho can suggest some help, please?