Having an issue migrating my customer from one Telco p-2-p T1 link to our telco p-2-p T1 link. Customer migrated two links on their own with no issues but the third link refuses to stay up. Fails after 30 seconds of communicating. Hub and Spoke setting with Cisco 2821 routers and WIC-1DSU-V2 modules. Tried changing protocols from HDLC to PPP with no success, swapped clock between routers, nothing. The routers work on the current CLEC link but not on ours. Since the old link is still being utilized, i can test with the new link. Placed Adtran routers on both ends and all worked great. Left then there for a couple of days and never logged any errors. Then placed Cisco 1841 router at Central site of link and all continued to work great - no errors at all on PPP. Placed Cisco router at remote end and kept Cisco router at Central Site - failed. Link comes UP/UP for around 30 seconds then fails. During the UP/UP, I can telnet between routers and communicate. Then the signal drops and link goes to DOWN/DOWN. Placed hard loop on Remote site. The Central site router detects loop and changes to UP/DOWN. Remove loop and goes back to DOWN/DOWN. Place loop at Remote site (on the cable that connects directly to the router) and Central site router detects loop - changes signal status to Up/DOWN. Remove loop and status returns to DOWN/DOWN. Customer insist it is the Telco but I can get every scenario to work except Cisco to Cisco. Are there any parameters on the WIC-1DSU-V2 module that I can tune to get the router to detect a signal from the Telco?