Can't dial out

[apb1963]

I have switched providers as suggested, in order to get survey mode working. I am getting an error as indicated below, and it won't dial out.

The original dialplan entry as generated by goauto/vicidial (no idea where those numbers came from):
exten => _8844765240.,1,AGI(agi://127.0.0.1:4577/call_log)
exten => _8844765240.,2,Dial(SIP/${EXTEN:10}@Switch2Voip,,tTo)
exten => _8844765240.,3,Hangup

The recommended/supplied dialplan entry by my new provider:
exten => _91XXXXXXXXXX,1,AGI(agi://127.0.0.1:4577/call_log)
exten => _91XXXXXXXXXX,2,Dial(SIP/${EXTEN:1}@switch2voip,,tTo)
exten => _91XXXXXXXXXX,3,Hangup

My modified entry after adjusting for the fact I have no "outside line" needing a "dial 9":
exten => _1XXXXXXXXXX,1,AGI(agi://127.0.0.1:4577/call_log)
exten => _1XXXXXXXXXX,2,Dial(SIP/${EXTEN}@switch2voip,,tTo)
exten => _1XXXXXXXXXX,3,Hangup

The error message in all cases:

[Jan 4 11:46:03] NOTICE[467]: chan_local.c:969 local_call: No such extension/context 652714342212138675309@default while calling Local channel
[Jan 4 11:46:03] NOTICE[467]: channel.c:5486 __ast_request_and_dial: Unable to call channel Local/652714342212138675309@default

(No idea where that extension/context is coming from.) Please advise how I can fix this.

Thank you in advance.